Vehicle-based applications for laser weapons
Vehicle-based applications for laser weapons are developing. Challenges faced by engineers in this regard is ensuring that there is sufficient space on a platform to accommodate the laser. (MBDA)

Although a few remaining hurdles are pushing the operational advent of laser weapons to the mid-2020s, they promise to bring cost-effectiveness and efficiency to the future capabilities equipping warships.

Upon hearing the words ‘laser weapons’ one cannot help but picturing Luke Skywalker, the hero of director George Lucas’ 1977 epic Star Wars, fiercely wielding his light sabre at his antagonist Darth Vader. The green light beam, the whirring sound as it moves and the way it retracts into the handle have all populated the dreams of generations of children, and science fiction geeks, alike. Today, as the film celebrates its 40th anniversary, we know that the light sabre will remain a figment of our imagination: science has proven that the amount of energy necessary to generate the light beam cannot be stored in a small handle, which would surely melt from the heat of the laser.

However scientific research has brought a new hope. While far from being readily available to armed forces around the world, a select number of countries, such as Germany, the People’s Republic of China, Russia and the United States have been successfully testing laser weapons to use against Unmanned Aerial Vehicles (UAVs), rockets and small boats. Some challenges have yet to be overcome, but industry is confident that the technology will be operationally ready by the mid-2020s.

The force Awakens

‘Laser’ stands for ‘Light Amplification by the Stimulated Emission of Radiation’. A laser includes a gain medium, primarily a solid, liquid or gas material that contains electrons that can be stimulated. For example a red laser, such as the type used to produce a red dot on a screen during a powerpoint presentation, may contain a ruby as its gain medium with a flash tube wrapped around it. In simple terms, an electric current makes the flash tube, or another light source illuminate. Every time this light source is illuminated light energy is pumped into the gain medium in the form of photons. Atoms comprising the gain medium absorb these photons by using their own electrons which forces them to increase to a higher energy level. Once these photons are absorbed by the atom’s electrons, the atoms return to their standard energy rate, by themselves emitting photons. These photons then move around the inside of the gain medium and every so often collide with an atom which is at that moment at a higher energy level. This causes the excited atom to product a photon (see above), thus we now have two photons where we would have had just one, and thus the original light has now been amplified. A mirror placed at one end of the laser tube causes these photons to keep bouncing around inside the gain medium producing yet more photons. Meanwhile a partial mirror located at the other end of the laser tube allows some of the photons to escape. These are the photons that form the laser light which escapes from the tube, and thus appear as a red dot on the presentation.

capability of lasers
Laser weapons can immobilise a target by burning a hole through the target’s skin to cause damage. The capability of lasers in this regard is graphically illustrated in this image. (US DOD)

When a laser beam is pointed at a target, it can cause damage by heating and, consequently, burning a hole into it, hence why laser technology is used to cut cloth. The more energy pumped into the gain medium, the stronger the laser beam will be and the more damage it will cause, especially if applied over a sustained period of time. The strength of a laser is expressed in terms of the electrical power it consumes, ranging from milliwatt (a typical laser pointer will produce around five millitwatts of light) to megawatts worth.

According to Alexander Chang, an associate at Avascent, a consultancy based in Washington DC: “Military applications of laser technology have been around for several decades, however, they have been subject to cyclical interest.” In the US, for instance, research around laser weapons received a major boost during President Ronald Reagan’s Strategic Defence Initiative (SDI), initiated in 1983. This initiative aimed to: “develop a space-based missile defence programme that could protect the country from a large-scale nuclear attack,” according to the US Department of State archives, including a space-based laser system, which earned it the nickname of the ‘Star Wars’ programme, causing elements of the popular press to call its initiator ‘President Ray-Gun’. With the end of the Cold War in the early 1990s, the SDI became obsolete and was quickly abandoned on cost grounds.

Since then, militaries around the world have been using lasers mainly for targeting and blinding missiles, waiting for the technology to mature enough to be able to weaponise these systems. For example, Northrop Grumman’s AN/AAQ-24(V) Directional Infrared Countermeasure uses laser light to protect aircraft by blinding an infrared-guided Surface-to-Air or Air-to-Air Missile (SAM/AAM) using the aircraft’s engine exhaust as its aim point.

Technology Strikes Back

Mr. Chang points out that: “in the last ten years we have seen a resurgence of interest in the development of laser weapons”. According to him, this is due to the fact that the technology has now matured to a point that overcomes a large number of the challenges previously preventing the weaponisation of the laser technology: “One of the key advantages of laser weapons is their favourable cost exchange ratio,” Mr. Chang added. A US Congressional Research Service (CRS) report entitled Navy Lasers, Railgun, and Hypervelocity Projectile: Background and Issues for Congress published in 2016 and written by Ronald O’Rourke, a specialist in naval affairs, stated that: “Unfavourable cost exchange ratios refer to the fact that a SAM used to shoot down a UAV (Unmanned Aerial Vehicle) or anti-ship missile can cost the navy more (perhaps much more) to procure than it cost the adversary to build or acquire the UAV or anti-ship missile.” The US defence budget for the year 2016 includes procurement costs for SAMs ranging from $900000 to several million dollars per missile, according to the report. Conversely, Mr. Chang continues: “navy officials estimate the laser cost-per-shot to be at less than $1.”

Another key advantage of laser weapons is the absence of ammunitions. As indicated by Dr. Rob Afzal, senior fellow at Lockheed Martin’s laser and sensor systems division: “a laser weapon can continue to fire as long as it is powered.” Compared to the storage space required for SAMs, for instance, this is a significant gain both in terms of room on-board the platform housing the laser and in terms of time needed between reloads to fetch the ammunition: “The fact that there is no need to store dangerous explosives on-board a platform also considerably plays in favour of laser weapons versus traditional ones,” adds Mr. Chang: “Overall, laser weapons have a distinct advantage in terms of tracking and hitting targets, as the beam moves at the speed of light,” concludes Dr. Afzal. Compared to other weapon systems, such as anti-aircraft guns, which need to aim ahead of an air target in order to account for the aircraft’s speed as well as the time needed by the projectile to reach the target, laser weapons are close to instantaneous. Moreover, lasers allow for graduated responses to a threat, ranging from monitoring targets to causing disabling damage by burning through the skin of aircraft or UAVs rendering them aerodynamically unstable. Karen Pachot, a spokesperson for MBDA, concludes: “The level of damage to any target would be dependent on the dwell time of the laser beam on the target, as well as the laser power.”

ground-based air defence
One promising application for laser weapons could be for ground-based air defence against UAVs. (MBDA)

Phantom Menace?

Despite the progress made in the last ten years, a number of challenges remain to be able to scale the power of laser weapons to a level where they can do serious damage to aircraft, ships or armoured vehicles. Mr. Chang points out that for now, one of the biggest challenges left to overcome is: “adaptive optics, that is, adapting the technology to deal with the loss of laser power incurred by air molecules and particulates to make sure that the beam is still strong enough to damage its target.” Essentially, as a laser beam passes through the air, it loses power because of interference caused by air molecules and water droplets, for instance. This causes the laser beam to scatter its light, therefore resulting in a loss of power. It is therefore imperative to ensure that the laser light maintains its destructive power when it reaches its target. Consequently, in environments with high humidity, a laser beam with originally 30 kilowatt (kw) of power might reach a target four kilometres (2.5 miles) away at a diminished power of 15kw.

The amount of energy necessary for powering lasers also constitutes a challenge. Currently, the laser weapons that have been tested only reach a limited amount of kilowatts, such as Lockheed Martin’s ALADIN 30kw fibre laser, which successfully disabled the engine of a small truck during a field test in early 2015; considerable amount of electricity needs to be channelled through the resonator to create this kind of power. This is not a problem for aircraft or ships which can harness the power of their engines to generate the necessary electricity. It remains, however, more limiting for ground vehicles, where the power source may have to come from a generator, which would take up precious space. Moreover, as indicated by Dr. Afzal: “Managing the residual heat generated from power that is not converted into the high power laser beam tends to be a limiting step.” Again, this could be overcome on aircraft, which can use their natural airflow, or for ships, which can accommodate the bulk of cooling systems, but it is again limiting for vehicles.

Lockheed Martin’s ALADIN laser
During tests, Lockheed Martin’s ALADIN laser weapon has demonstrated its ability to disable the engine of land vehicles, which it achieved during field tests in 2015. (Lockheed Martin)

One final issue relates to the potential collateral damage done by a laser that misses its target. Although laser weapons significantly increase precision for hitting targets, there is always the possibility of a mistake. As Mr Chang asks: “what would happen, then, if the laser beam reached the atmosphere and hit a satellite, for instance?” As such, at present laser weapons are unlikely to become an imminent offensive menace, and will instead continue to be conceived and used primarily as defensive weapons. According to Paul Shattuck, director and chief engineer of directed energy systems at Lockheed Martin: “we expect laser technology will be a force multiplier: (troops) will use laser weapons together with kinetic weapons to disable threats like UAVs, small rockets, mortars and lightweight ground vehicles.”

Vehicle-based applications for laser weapons
Vehicle-based applications for laser weapons are developing. Challenges faced by engineers in this regard is ensuring that there is sufficient space on a platform to accommodate the laser. (MBDA)

United States

Although the SDI (see above) did not succeed in its original endeavour, the US military has, throughout the years, continued to invest in the development of laser weapons. According to Mr. Chang: “the navy has been the most aggressive of all military arms in the US to develop the laser weapon, followed closely by the US Air Force Special Operations Command (AFSOC), primarily because (on aircraft) there are less issues regarding space and cooling.”

A first attempt at testing a laser weapon began in 1996 equipping a Boeing 747-400F turbofan freighter with a chemical pumped laser. The YAL-1 Airborne Laser Testbed, as the aircraft came to be known, was used by the US Department of Defence’s (DOD) Missile Defence Agency, and carried a chemical oxygen iodine laser that could track and destroy a ballistic missile during its boost phase, after the missile has been launched, but before the missile reached its peak velocity. Unfortunately, while successfully destroying targets during the test phase, the YAL-1 only ever achieved a very limited range for the destruction of Intercontinental Ballistic Missiles (ICBM) during their boost phase, typically of up to 162 nautical miles (300 kilometres) according to US DOD figures for a significant cost of $100 million per year for the YAL-1’s development programme. The range problem meant that the YAL-1 would potentially have to place itself within range of an adversary’s SAMs when engaging an ICBM. The US DOD took the decision to discontinue the initiative in 2011 due to the high cost of the programme compared to the limited range achieved thus far. It is also likely that this coincided with a general loss of interest in the industry for chemical lasers, deemed too dangerous to be carried on-board planes or ships according to Mr. Chang.

Since then, between 2009 and 2012 the US Navy has tested, initially on land and then on board the USS Ponce, ‘Austin’ class amphibious assault ship, the 30kw AN/SEQ-3 Laser Weapon System (LAWS) from August 2014, with the vessel equipped to this end deploying to the Persian Gulf. where the laser successfully destroyed UAVs and other targets in test shots. It has remained operational on board the USS Ponce since then. Additionally, between 2010 and 2011, Northrop Grumman installed its Maritime Laser Demonstration (MLD) on the navy’s Self Defence Test Ship, the USS Paul F. Foster, to test it on small moving targets. According to the company website: “the high energy laser demonstrator successfully tracked and defeated multiple moving small boat targets at operationally significant ranges”. As a follow-on effort to the AN/SEQ-3 and MLD, in 2012 the navy’s Office of Naval Research (ONR) initiated the Solid State Laser Technology Maturation Programme (SSL–TM). According to the ONR website, the SSL-TM: “will develop and mature high-energy laser technologies into a prototypical weapon system for use and installation on the navy’s surface combatants.” In December 2015, Northrup Grumman won the SSL-TM competition, signing a contract worth approximately $53 million, according to the report from the CRS, to develop a laser producing between 100kw and 150kw of power. The author contacted Northrup Grumman for more information regarding this initiative, but received no response by the time Armada went to press.

The AFSOC, on the other hand, is working to develop a laser to be fitted on board its Lockheed Martin AC-130 family fixed-wing gunships. Military scientists aim for the programme, known as the Self-Protect High-Energy Laser Demonstrator (SHIELD), to develop a laser pod validated in a laboratory environment by 2017, and have a prototype ready for 2021, according to the US DOD’s Request For Information notice pertaining to this initiative. Finally, under the High Energy Laser Mobile Demonstrator (HELMD) programme, the US Army is developing laser weapons that can be mounted on armoured vehicles. To this end, by late 2017 Lockheed Martin will deliver a 60kw laser to the army, according to Dr. Afzal and Mr. Shattuck. By 2022 the US Army expects to scale-up to a 100kw system, although it has yet to be determined who will develop it.

Europe

Away from the United States, in September 2016, the UK Ministry of Defence (MOD), announced that it had finalised a $37 million deal with UK Dragonfire, a UK industrial team led by MBDA, for the development of a new laser demonstrator. According to the MOD announcement, the Laser Directed Energy Weapon (LDEW) Capability Demonstrator: “will assess how the system can acquire and track targets at range and in varying weather conditions over land and water, with sufficient precision to enable safe and effective engagement”. Ms. Pachot specifies that: “MBDA will bring prime weapon system delivery experience and advanced weapon system C2 (Command and Control) and image processing capability, and will coordinate the efforts of QinetiQ (laser source research and demonstration expertise), Leonardo (advanced optics, pointing systems and target tracking), GKN (innovative high power storage capability); BAE Systems and Marshall Land Systems (maritime and land platform integration advice respectively), and Arke (independent support to through life costings and Defence Lines Of Development considerations)”. The first prototype will be presented in a demonstration in land and maritime environments in 2019, which will include initial detection and engagement planning, handover to the beam director, pointing and tracking, engagement, battle assessment and follow-on engagement capability, according to Ms. Pachot.

MBDA Germany is also working on a concept combining the use of commercially-available high power laser sources and a self-developed pointing and tracking, beam forming and beam direction system. The ensemble is expected to be deployable on different land, air and sea platforms, and should be tested by the end of this year. For target acquisition and tracking, the system relies on the use of external sensors, whereas for target hitting, Ms. Pachot specifies: “MBDA developed the ‘geometrical coupling’ of multiple laser beams.” This means that a number of individual high-power fiber laser beams are combined together using one common beam director telescope.

Meanwhile, in 2013, Rheinmetall demonstrated its High Energy Laser Effector (HEL). In 2013, the company has demonstrated the HEL at its Ochsenboden proving grounds, in east Switzerland, where the system was mounted on an ARTEC Boxer family eight-wheel drive armoured fighting vehicle, a modified United Defence/BAE Systems’ M-113 family tracked armoured personnel carrier, and a Tatra eight-wheel drive truck. The laser power ranged from 1kw to 50kw and, according to the company’s press release: “demonstrated how radio antenna, radars, ammunition, power supply systems and entire weapons systems can be neutralised or destroyed with minimum collateral damage.”

Asia-Pacific

As with all things Russian and Chinese, little information is readily available regarding the types of laser weapons that are currently being developed in these countries or, for that matter, the power of these weapons or when they will become operational. Nevertheless, various local sources indicate that programmes are on going. Russia has been working on the development of laser weapons since 1964, conducting tests at Terra-3, a Soviet laser testing centre located on the Sary Shagan anti-ballistic missile testing range in Kazakhstan. In August 2016, speaking at an event commemorating the 70th anniversary of the All-Russian Research Institute for Experimental Physics in Sarov, central Russia, deputy defence minister Yuri Borisov said that the Russian armed forces were in the process of commissioning and even adopting several types of laser-based weapons.

Conclusion

Mr. Chang concludes that: “It is difficult to say with certainty when laser weapon technologies will be operationally deployed, and there is still a lot of scepticism from people who have seen interest grow and wane over the decades.” Mistakes in the past that have led to loss of interest, however, may have been the result of industry and policy makers aiming too high from the start, rather than fundamental flaws in the technology itself. The string of successful tests, from the US to Germany, clearly shows that, according to Mr. Chang: “Laser weapons need to develop incrementally, scaling up the energy to meet progressively larger threats.”

Progressive development also allows the industry to progressively address challenges. Lockheed Martin, for instance, is working on the development of fibre lasers, which use fibre optic technologies to create the laser beam. It successfully demonstrated the firm’s ALADIN, a 30kw spectral beam combining fibre laser in early 2015 (see above). According to Mr. Shattuck: “this will allow laser weapons to put more energy on target and compensate for changes in air temperature and other atmospheric variables that hampered earlier later technologies.” Increasing the precision of laser weapons also leaves room for the progressive development of a technology for which the rules of war have yet to be established. Currently, the only international document pertaining to laser weapons is the 1980 United Nations’ Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons which may be deemed to be Excessively Injurious or to have Indiscriminate Effects. However, this convention only addresses low power laser weapons: “specifically designed as their sole combat function or as one of their combat functions to cause permanent blindness to unenhanced vision.” Over the long term, laser weapons may become a reality on the battlefield: “Practical and cost-effective directed energy systems can be integrated on existing land, sea and air platforms beginning in the 2020-25 timeframe following concerted technology maturation and demonstration efforts,” concludes Mr. Shattuck.

by Dr. Alix Valenti