Lasers Adapt to Changing Threat Landscape

MARIE FREEBODY, CONTRIBUTING EDITOR, marie.freebody@photonics.com

The danger facing today’s global defense force is shifting. With the rise in unmanned aerial vehicles (UAVs) and enemies gaining greater ballistic missile expertise, ultraprecise and quick-response laser systems are attracting more interest than ever before.

Lasers offer a low-cost-per-shot solution to high-volume threats posed by drones and also offer the deep magazine capability to address multiple targets with reduced logistics tails. For many years, lasers have been used in a variety of defense applications, from determining target ranges, to precisely delivering munitions, to confusing or jamming optical trackers, and as weapons to dazzle personnel or destroy targets. MIR lasers are even used to counter IR-guided missiles.

This illustration shows Boeing’s Compact Laser Weapon System integrated onto a combat vehicle for effective short-range air defense against unmanned aerial vehicles (UAVs). (Note that lasers are invisible, so the colored beam is for effect.) Courtesy of Boeing.

“Laser weapon systems provide a viable, affordable solution to the challenges warfighters face today,” said Queena Jones of Space and Missile Systems at Boeing Defense, Space & Security. “Useful in ground, maritime and airborne applications, the scalable effects of laser systems address a wide range of threats, from defeating optical sensors to disabling airborne mortars.”

Neutralizing enemy drones

Before firing the first shot, the threat must be accurately located and followed. When it comes to range-finding and tracking, lasers offer the flexibility and adaptability to support a wide range of missions.

For example, Boeing’s acquisition, tracking and pointing (ATP) capability is key to enabling the rest of the laser weapon system to perform properly. In 2010, Boeing first showcased ATP capability on programs that included the air-to-ground Advanced Tactical Laser (ATL), which was demonstrated on a C-130 aircraft against moving ground targets.

The next step was to tackle targets in the air. In 2013, Boeing delivered the High Energy Laser Mobile Demonstrator (HEL MD) to the U.S. Army to disable airborne mortars. Today, Boeing’s Compact Laser Weapon System (CLWS) is being integrated on ground-based Stryker combat vehicles to provide defense against low, slow UAVs.

Boeing’s Compact Laser Weapon System is being integrated on ground-based Stryker combat vehicles to provide defense against low, slow UAVs. Courtesy of Boeing.

Commercially available lasers are combined with Boeing’s beam director Technology, which helps guide the laser to precise targets. In the setup, the CLWS operator uses a video display to identify, acquire and lock onto the target. Once acquired, the system autotracker locks on and maintains a fixed track of the target.

Next, the operator selects a specific part of the target and keeps the beam fixed on that spot. Much like a welding torch, sufficiently high energy is directed to a spot small enough to heat up and damage the target. In the case of a UAV, the heat eventually disables it, causing it to drop to the ground. Unlike a welding torch, however, the CLWS can operate from many hundreds of meters away.

Lockheed Martin ATHENA (Advanced Test High Energy Asset) laser weapon system defeats a truck target by disabling the engine from nearly a mile away with a 30-kW beam, demonstrating its military effectiveness against enemy ground vehicles. Courtesy of Lockheed Martin.

In the last year, Boeing laser weapon systems have disabled more than 100 UAVs of various types for the equivalent cost of fuel a Stryker vehicle would require to take down the same number of UAVs.

Since these aircraft pose low-budget yet high-volume threats, cost-effective solutions are needed to keep the U.S. military on the right side of the cost curve.

“The CLWS is based on technology and components that exist now — there is no additional technology development required and it provides an opportunity for the transition to the warfighter today,” Jones said.

“From a cost perspective, laser weapons continue to show the ability to provide a cost-effective solution.”

Laser weapons take to the skies

Ground- and sea-based laser systems have been technically demonstrated, but when it comes to active deployment, the only laser weapon system now in military operation is found on the U.S. Navy’s USS Ponce. Developed under the Office of Naval Research’s Solid State Laser Technology Maturation program, shipboard lasers benefit from being electrically powered by a ship’s existing power system.

As opposed to chemically powered lasers, solid-state lasers do not require the ship to be periodically resupplied with chemicals. This avoids unnecessary removal from the battlefield and risky loading and storing of toxic chemicals on board. At the cost of about one dollar per shot, this ship-based solid-state laser can fire a 33-kW beam to counter airborne and surface-based threats at the speed of light, which means operators don’t have to worry about wind or even range. It is as simple as pointing and shooting.

With performance credentials such as these, it’s little wonder that the U.S. Army, Air Force and Navy have major laser weapon system development programs underway, with each service looking to deploy them in the near future.

Earlier this year, Lockheed Martin delivered a 60-kW laser to the U.S. Army for its short-range air defense mission, to be installed on a ground vehicle with the goal of countering rockets, artillery and mortars, and small UAVs.

Although land- and sea-based laser weapon systems enjoy more freedom of design, it’s a completely new and different challenge to get a laser system into a small, airborne test platform.

One of the key challenges has been reducing the size, weight and power of the systems to make them tactically deployable on an aircraft. The technology really took off with the advent of fiber optics, and in the past few years, great strides have been made to shrink the size, weight and power consumption of these systems.

“Moreover, the laser efficiency significantly reduces the power and cooling requirements, enabling the demonstrations you’re seeing today from the services,” said Rob Afzal, a senior fellow of Laser Weapon Systems at Lockheed Martin.

In November 2017, Lockheed Martin was awarded $26.3 million by the U.S. Air Force Research Lab (AFRL) to design, develop and produce a high-power fiber laser, which it plans to test on a tactical fighter jet by 2021.

The contract is part of the AFRL’s Self-protect High Energy Laser Demonstrator (SHiELD) program and is being seen as a major step forward in the maturation of protective airborne laser systems. Contracts were also awarded to Boeing to develop the pod in which the laser will be housed, and to Northrop Grumman, which is responsible for the beam control system that will track targets, compensate for atmospheric conditions that could distort the laser beam, and focus the outgoing beam on the target.

Lockheed Martin will develop a high-power fiber laser, known as LANCE (Laser Advancements for Next-Generation Compact Environments), which will focus high-power energy on a target to disable threats.

Lockheed Martin can’t address specifics of the technology or the types of threats, but the AFRL has confirmed that LANCE will be used for testing self-defense against air-to-air and ground-to-air weapons.

Northrop Grumman’s LITENING is a combat-proven, self-contained, multisensor targeting and surveillance pod in use by U.S. and international customers. Courtesy of Northrop Grumman.

“Lockheed Martin sees promise for the use of high-power fiber lasers in many defense applications,” Afzal said. “To date, we’ve delivered a high-power fiber laser to the U.S. Army as part of their Robust Electric Laser Initiative (RELI) program. We’re continuing to invest with our customers to reduce the size, weight and power of systems to allow for integration on planes, ground vehicles and ships.”

Arming warfighters

The precision engagement, scalable effects and deep magazine capabilities are major advantages that only laser weapon systems can offer. Yet experts believe that lasers are unlikely to become the end-all weapon system; for now, anyway, they will be used to augment existing solutions, giving warfighters a mix of kinetic and directed energy solutions.

“We’ve come a long way with lasers, but to continue to advance them, the main challenge and opportunity we face is reducing the size, weight and power consumption of the systems,” Afzal said. “Power is critical, because the more efficient a system we can build, the smaller the generator we need to power it.”

For example, if a 50-kW generator can be made to power a 50-kW beam, there will be no “waste” powering the system. This carries over into size and weight: If the size and weight of the required generator can be reduced, then lasers could find themselves on ever-smaller platforms — moving from a ship to perhaps one day a helicopter or even a hand-held laser.

Shown here is the Northrop Grumman Guardian pointer-tracker, which directs laser energy at an incoming missile’s seeker. Northrop Grumman’s infrared countermeasure systems are currently installed on a wide range of aircraft, including both rotary- and fixed-wing platforms. Courtesy of Northrop Grumman.

Other challenges relate to the harsh environments often experienced in defense applications. Some commercial environments can be controlled in terms of temperature and vibration, but when it comes to defense applications, lasers must reliably work in severe temperature extremes and often with harsh vibration levels.

These environments task the laser designer with the difficulty of maintaining alignment of optical components and minimizing heat impacts on the system. This will take time, concentrated design solutions and qualification efforts to overcome.

Technological and environmental challenges aside, there are also difficulties that must be navigated when it comes to updating governmental policies on the use of laser weapons. Boeing’s Jones believes this is one of the biggest obstacles to getting lasers for defense applications off of the science and technology testing grounds and into the hands of the war- fighter.

“Another major challenge of introducing a new weapon system is tactics, training and procedures,” Jones said. “During the Army’s Maneuver Fires Integrated Experiment 2017 event at Fort Sill [Okla.], we trained warfighters to operate the CLWS, and they successfully engaged multiple UAV targets.”

These types of experiments help to guide the concept of operations on the battlefield with existing command and control infrastructure.

“Introducing new weapons and technology always includes challenges,” Jones said, “and we are working with the [U.S.] Department of Defense to overcome them today.”

Turning Lasers Into Weapons

For as long as lasers have existed, many people have been interested in their defensive applications. The challenge has historically been reducing the size, weight and power of the systems to make them tactically deployable.

For decades, lasers were sorely lacking in power efficiency. For example, a 10 percent efficiency meant that to emit a 100-kW beam, a 1000-kW generator would be needed, which would generate 900 kW of heat. The power and cooling required made the weapon system simply too large to be deployed on tactical platforms.

But thanks to major advances across various commercial sectors, lasers have enjoyed a journey from early warning system right through to formidable weapon.

When Paul Lang, now technical director in the Common Infrared Countermeasures programs of Northrop Grumman Mission Systems, first started working in defense 34 years ago, lasers were already in use. His first project was working on sensors to detect laser threats to warn aircrews that they were being targeted.

“This original laser development used gas lasers that were heavy, inefficient and frankly not practical to field,” Lang said. “But we saw the potential of these lasers over other technologies, so we kept working on developing better lasers for these applications. As the technology matured, nonlinear optical materials were developed that made these lasers smaller, more efficient and more powerful so they could be fielded on defense platforms.”

Today, there are now powerful, multiband lasers at the disposal of researchers, which are fielded on a variety of defense platforms. The continued push for even more advanced technology has led to those such as the Quantum Cascade Laser, which does not require a complex optical chain.

“Many of the lasers we see our military customers using began as commercial laser applications,” Lang said. “The high-speed fiber optic links that bring high-definition video into your living room are used on defense platforms to handle the increasing amount of data these platforms process.”

Today, lasers are used as rangefinders to measure the distance to a target. They are used to accurately designate a target for weapons delivery, which has greatly reduced collateral damage. Lasers work well as beacons or long-range illuminators for optical sensors. They are used to confuse or jam optical sensors, including infrared missiles or nonlethal dazzling of personnel.

Lasers will undoubtedly remain a core technology for defense applications. That’s not going to change. They perform their functions well, and there are few, if any, competing technologies for things such as a hand-held rangefinder.

“Lasers have distinct advantages. They perform in ways that no other device can replace,” Lang concluded. “We see laser technology as continuing to mature, and we are working to deploy them for evolving threats.”