Laser weapons development is pushing laser technology out of the laboratory and into directed-energy weapons applications in the field
Light sabers and blasters in Star Wars, phasers on Star Trek, the heat-ray in H.G. Wells’s War of the Worlds, and rayguns and death rays in myriad films from the 1960s and 1970s. The phrase "laser weapon" most often conjures images of these and other fictional, futuristic devices. In reality, laser weapons are currently undergoing testing and likely to be fielded in the very near future.
Military lasers enjoy a long history in laser rangefinder, laser radar (ladar), laser target designator, and even laser countermeasures applications. Much work is now being done in the area of laser weaponry, but "the broad use of military laser technology has been as sensors and ways of communicating information across a distance," acknowledges Daniel Nieuwsma, senior principle physicist of the Optics and Lasers Department at Raytheon Space and Airborne Systems in El Segundo, Calif. (See related story, Latest generation of laser weapons confronts systems designers with formidable thermal management and cooling issues)
Mil-aero use
"The benefits of lasers relate to the ways that they are employed," says Bob Byren, principal engineering fellow, EO/IR & Laser Technology Area Director, SAS Engineering, Raytheon. "Laser beams by their nature are highly collimated, which means they allow energy to be transmitted over long distances through a small aperture with very little angular dispersion." This property is used in all military laser applications, such as laser rangefinders and designators. "You’ve got to put a small spot on a target at a long distance--that’s the chief property of lasers that makes it so useful.
"Laser beams are also monochromatic, which means they come out in a single color," Byren adds, "and that’s very useful in many applications, such as laser radar, that allow you to filter out the noise from solar-reflected energy which would otherwise compete with a laser beam." That monochromatic property also enables the measurement of narrow absorption lines in chemicals, delivering the ability to distinguish chemical clouds and biological agents from naturally occurring phenomena.
"Laser beams can be modulated either as pulses or as a form of coherent modulation, which makes them useful for communications and many forms of laser radar, such as 3D imaging and vibrometry," Byren notes. "Lasers are also capable of projecting a lot of power, which makes them useful for weapons in their own right."
Golden anniversary
The first working laser was built on 16 May 1960--50 years ago last month. Theodore Maiman produced the innovation at Hughes Research Laboratory, the research arm of Hughes Aircraft Company, founded by Howard Hughes in Culver City, Calif. Maiman’s laser was not publicly announced until 7 July 1960, when it reportedly caused great concern and prompted headlines about potential death rays. Public predictions were not terribly far off the mark, and lasers were soon employed in battle -- but they were hardly "death rays."
Engineers in "the defense part of Hughes Aircraft immediately found [the laser] useful as a very precise rangefinder, and started building the first laser rangefinder in 1961 and 1962," Nieuwsma adds. A large number of projects related to laser sensors and rangefinders followed, and by 1967 the company started the first military-qualified laser in production: a rangefinder for the M60A2 main battle tank.
Laser-guided weapons were first developed in the United States in the early 1960s. The U.S. Air Force issued the first development contracts in 1964, which lead to the development of the Paveway series of laser-guided bombs (LGBs). Texas Instruments, Raytheon, and Lockheed Martin were involved in the production of LGBs. "Raytheon Company introduced the first laser-guided precision munition operating during the Vietnam War" in the late 1960s, according to a company spokesperson.
"The Hughes legacy went on, and in 1968 built the first laser target designator for the Army," Nieuwsma explains. "It was a test item--a laser that sends out a code of pulses reflected off a target, so that laser homing munitions, such as missiles or bombs, can home in very precisely on that target." The technology was of great benefit in both Gulf wars, he says. "We were able to take out an anti-aircraft gun put next to a school or a hospital, for example; we wouldn’t hurt the school or hospital because we could very precisely target it against only the military item."
More milestones
Prime contractors, research labs, and academia continue to advance laser technologies, especially in the realm of laser weaponry. Several laser weapon milestones have occurred this year alone (specifically, between January and April of 2010).
Three heavyweights -- Boeing Defense, Space & Security in Berkeley, Mo.; Northrop Grumman Corp. in Redondo Beach, Calif.; and Lockheed Martin in Bethesda, Md. -- began collaborating on the Airborne Laser program for the U.S. Air Force in 1996. In 2001, it was converted to an acquisition program under the Missile Defense Agency (MDA).
Each member of the Boeing ABL team contributed a different facet of what is now the Airborne Laser Test Bed (ALTB), which on 11 February 2010 applied a lethal amount of directed energy to destroy a boosting ballistic missile target, or tactical ballistic missile (TBM). The proof-of-concept demonstration marked the first directed-energy lethal intercept demonstration against a liquid-fuel boosting ballistic missile target from an airborne platform.
"While ballistic missiles like the one ALTB destroyed move at speeds of about 4,000 miles per hour (mph), they are no match for a super-heated, high-energy laser beam racing towards it at 670 million mph," a Northrop Grumman official says of the landmark event. "The basketball-sized beam was focused on the foreign military asset, as the missile is called officially, for only a few seconds before a stress fracture developed, causing the target to catastrophically split into multiple pieces."
ABL construction
Two solid-state lasers and one high-energy, chemical laser housed in a modified Boeing 747-400F, in addition to various avionics and electro-optics, comprise the ALTB. The back-half of the Boeing Freighter encloses Northrop Grumman’s high-energy, megawatt-class Chemical Oxygen Iodine Laser (COIL) –being called the most powerful laser ever developed for an airborne environment. Northrop Grumman also contributed the low-power, kilowatt-class, solid-state Beacon Illuminator Laser for atmospheric compensation and targeting. The front section of the aircraft contains the battle management system, provided by Boeing, and the beam control/fire control system, developed by Lockheed Martin.
Raytheon developed for Lockheed Martin the Track Illuminator Laser (TILL), the first diode-pumped Yb:YAG (ytterbian yttrium aluminum garnet) laser qualified for flight operation aboard a military aircraft. "[It] allows the system to track the hard body of the missile and not be confused by the very bright plume that the rocket engine puts out," says Raytheon’s Byren. "It was the first fielded ytterbian laser in military applications." Onyx Optics Inc. in Dublin, Calif., supplied the laser gain medium and diffusion bonding to Raytheon, whereas Scientific Materials Corp. in Bozeman, Mont., provided the Yb:YAG rod for that system.
"The continued dependable and consistent performance of both laser systems is the result of our dedicated team and its unwavering commitment to develop game-changing technology for our military forces," says Guy Renard, Northrop Grumman's ALTB program manager. "The impressive progress made by the government and industry team during the last three-and-a-half years could not have culminated any more dramatically than this successful experiment."
The test, conducted by Boeing and the MDA, impressed many high-level military and government officials. The Air Force’s fiscal 2010 budget does not allot funding for further Airborne Laser research and development, however; the U.S. military still has money to pursue the research of directed-energy laser weapons.
Air Force Chief of Staff Gen. Norton Schwartz, who witnessed the shootdown first-hand, called it a "magnificent technical achievement" but said the Airborne Laser "does not reflect something that is operationally viable." When questioned about the future of directed-energy lasers, Schwartz responded in favor of solid-state, rather than chemical, lasers. "That’s the queen of the realm, sir."
Solid-state successes
"I think the industry is moving away from chemical lasers because of the toxicity, corrosion, and problems with logistics support. The current push now is to use solid-state lasers to achieve very high powers," explains Byren of Raytheon, which is now exclusively a solid-state laser house.
Accelerating the development and advancement of solid-state laser technology for military applications is the Joint High Power Solid State Laser (JHPSSL) program, currently in Phase 3. Engineers from Northrop Grumman and Textron Defense Systems in Wilmington, Mass., are working on the current phase of the JHPSSL, which is funded by the Office of the Assistant Secretary of the Army for Acquisition, Logistics, and Technology; Office of the Secretary of Defense – High Energy Laser Joint Technology Office, Albuquerque, N.M.; Air Force Research Laboratory, Kirtland Air Force Base, N.M.; and the Office of Naval Research, Arlington, Va.
Under the JHPSSL program, Northrop Grumman surpassed a critical milestone (in Phase 2) when it demonstrated a laser system with a total power of greater than 27 kilowatts (kW) with a run time of 350 seconds; and, it became the first company to reach the 100kW power level threshold for a solid-state laser. The latter achievement also included a turn-on time of less than one second and continuous operating time of greater than five minutes with good efficiency and beam quality.
Under the current phase (Phase 3), says a representative, the goal is for a laser system to reach 100 kW, setting the stage for a variety of force protection and strike missions, such as shipboard defense against cruise missiles; wide-area, ground-based defense against rockets, artillery, and mortars; and precision strike missions for airborne platforms.
Northrop Grumman’s solid-state laser system -- which produced the most powerful beam ever from a continuous wave, electric laser in 2009 -- is slated to enter field tests this year at the Army's High Energy Laser System Test Facility (HELSTF), N.M. BAE Systems, in cooperation with the U.S. Army's Space and Missile Defense Command/Army Forces Strategic Command, has contracted with Northrop Grumman to relocate the Joint High Power Solid State Laser (JHPSSL) Phase 3 system from the company's laser factory in Redondo Beach, Calif., to HELSTF.
At HELSTF, this laser will integrate with the beam control and command and control systems from the Northrop Grumman-built Tactical High Energy Laser (THEL), to provide the Army with the world's first high-power, Solid State Laser Testbed Experiment (SSLTE). The SSLTE will be used to evaluate the capability of a 100kW-class, solid-state laser to accomplish various missions; the results will be the basis for directing future development of solid-state lasers as a weapon system, reveals a Northrop Grumman representative.
"Solid-state lasers have achieved militarily useful power levels and packaging densities," admits Dan Wildt, vice president of Directed Energy Systems for Northrop Grumman's Aerospace Systems sector. "We have been demonstrating laser performance at HELSTF and other test sites for many years, unequivocally proving their lethality against a wide variety of potential threats." Among them are missiles of various sizes and speeds, helicopters, drones, rockets, artillery, mortar rounds, and submunitions.
BAE Systems, headquartered in Rockville, Md. and under contract with the U.S. Army, has overall responsibility for the SSLTE systems engineering and test planning, as well as the development of the modular, transportable enclosure housing for the JHPSSL device and its control room at the site.
Free electron design
Engineers at The Boeing Company -- specifically, The Boeing Missile Defense Systems Directed Energy Systems unit in Albuquerque, N.M., and the Boeing Research & Technology group in Seattle -- have completed the preliminary design of the U.S. Navy’s Free Electron Laser (FEL) weapon system. The achievement is being called "a key step toward building an FEL prototype for realistic tests at sea."
The electric laser passes a beam of high-energy electrons through powerful magnetic fields, generating an intense emission of laser light that can disable or destroy targets, reveals a company official. In April 2009, Boeing won an initial $6.9 million, Office of Naval Research task order to begin developing FEL. Boeing has partnered with U.S. Department of Energy laboratories, academia, and industry partners to design the laser.
The project could potentially reach $163 million, if the Navy awards Boeing additional task orders this summer to complete the FEL design and build a functional laboratory demonstrator.
Vehicle-borne laser
Boeing engineers are outfitting a Heavy Expanded Mobility Tactical Truck (HEMTT) from Oshkosh Defense, a division of Oshkosh Corp. in Oshkosh, Wis., with a Boeing-built laser beam control system for the U.S. Army's High Energy Laser Technology Demonstrator (HEL TD) program.
"This demonstration program has transitioned from the design phase to the fabrication phase," acknowledges Gary Fitzmire, vice president and program director of Boeing Missile Defense Systems’ Directed Energy Systems unit. "This transformational, solid-state laser weapon capability will provide speed-of-light, ultra-precision capability that will dramatically improve warfighters' ability to counter rocket, artillery and mortar projectiles."
The eight-wheel, 500-horsepower HEMTT A4 military tactical vehicle is being integrated with the laser's rugged beam control system (BCS) at Boeing's Huntsville, Ala., facility. The BCS is designed to acquire, track, and select an aim point on a target; the system will simultaneously receive the laser beam from the laser device, reshape and align it, and focus it on the target using mirrors, high-speed processors, and optical sensors.
"The program is making great progress and getting closer to demonstrating its revolutionary capability," observes Blaine Beardsley, Boeing HEL TD program manager. In fact, the HEL TD is scheduled to be tested against real targets, using a low-power surrogate for the high-energy laser, in fiscal year 2011 at White Sands Missile Range, N.M.
Paveway longevity
The Paveway legacy lives on with Lockheed Martin’s Paveway II Plus laser-guided bomb, which completed a series of six flight tests at Eglin Air Force Base, Fla., on 3 March 2010. The "Plus" model sports an enhanced laser guidance package, designed to improve precision over Paveway II LGBs.
During the tests, Paveway II Plus systems were launched from altitudes ranging from 10,000 to 30,000 feet against a 24-by-24-foot billboard target at a 45-degree angle. "Two [Guided Bomb Unit] GBU-10s and four GBU-12s equipped with MAU-209C/B computer control groups were released from a pair of F-16D Viper jet aircraft from Eglin’s 40th Flight Test Squadron," explains a Lockheed Martin spokesperson. "Each initiated laser acquisition at the expected time and guided to the intended target."
Paveway II laser-guided bomb guidance kits increase weapon accuracy, reducing risk to U.S. and allied ground forces by converting gravity weapons into precision-guided munitions. A computer control group serves as the LGBs front-end guidance system, while an air foil group with stability fins on the back of each weapon delivers lift and aerodynamic stability for in-flight maneuvering.
Lockheed Martin is a provider of the Paveway II LGB and all three variants of the Paveway II MK-80 series LGBs; is the sole provider of the Paveway II Enhanced Laser Guided Training Round and Dual Mode Laser Guided Bomb; and has delivered more than 55,000 LGB kits to the U.S. Air Force, U.S. Navy, and international customers.
Mine detection
ALMDS, mounted on the side of an MH-60 helicopter, detects and locates floating and submerged mines, which pose a threat to U.S. and allied military and commercial ships. In day or night, the system uses pulsed laser light and streak tube receivers in an external equipment pod to image the near-surface volume area of the sea in 3D. The ALMDS is capable of operations.
ALMDS will be coupled with Northrop Grumman's RAMICS, now in development. RAMICS, also operating from an MH-60S helicopter, will use the mine location information from ALMDS, relocate the mine, and neutralize it with a 30-millimeter gun. Both systems are part of the Mine Counter Measures (MCM) Mission Package to be deployed on Littoral Combat Ships. Northrop Grumman also serves as LCS Mission Package Integrator for the Navy.
Northrop Grumman engineers, who produce the ALMDS at the company’s Melbourne, Fla., facility, achieved the early deliveries with the teamwork of Naval Sea Systems Command PMS 495; the Naval Surface Warfare Center, Panama City Division, Panama City, Fla.; and the Defense Contracts Management Agency; as well as Areté Associates, Tucson, Ariz., which manufactures the Receiver Sensor Assembly; Cutting Edge Optronics, a Northrop Grumman subsidiary in St. Charles, Mo., which manufactures the high-powered laser transmitter; CPI Aero, Edgewood, N.Y., manufacturer of the pod housing; Curtiss Wright/DY4, San Diego, manufacturer of the central electronics chassis; and Meggitt Defense Systems, Irvine, Calif., which produces the environmental control system.
Northrop Grumman's Melbourne facility, the company's Center of Excellence for Airborne Mine Countermeasures, is under contract to develop the U.S. Department of Defense's four Airborne Mine Countermeasures sensor programs.
"The Northrop Grumman contractor team and our Navy partners are working hard to get these systems into the fleet as quickly as possible," says Dan Chang, vice president of Northrop Grumman Maritime and Tactical Systems. "ALMDS and the Rapid Airborne Mine Clearance System (RAMICS) are critical tools with demonstrated technologies for getting our warfighters out of minefields. These two programs are key to the fielding of the entire mine detection and destruction capability to our warfighters."
Laser reflections
The military has long reaped the benefits of laser rangefinders, target designators, and sensors on the battlefield. "They want to provide that to almost every platform and every soldier," says Nieuwsma. "They are looking to decrease the size, weight, and power (SWaP) so they can run on cell phone-style batteries. SWaP is the big push on the targeting end of lasers and we’re working some advanced concepts with planar waveguide lasers to make very compact lasers to fill that niche for the military."
Compact and efficient, lasers are well suited to achieving SWaP goals. "Affordability is another big issue," says Byren. "The planar waveguide laser architecture, it turns out, is amenable to many different military applications: from the low-end, which includes laser rangefinders, all the way up to the high-end, directed-energy weapons.
Cooling is another major factor to consider in the design of modern, high-energy laser systems. "Advanced cooling technology is one of the gate keepers to deploying a high-energy laser on a small tactical aircraft," explains Dr. Dan Rini, president of RINI Technologies in Oviedo, Fla. Without adequate cooling, the laser just won’t function: efficiency is lost, wavelengths are incorrect, and it can catastrophically fail.
"Standard cooling techniques work great in the lab," Rini continues, "but they don’t necessarily transition well to military environments. You need advanced cooling techniques to make [laser systems] lighter and smaller."
Many technology firms are also working to advance ladar, or laser radar, for mil-aero applications. Raytheon is involved in a program called SALTI, Synthetic Aperture Ladar for Tactical Imaging. "It is the first successful application of synthetic aperture radar techniques to optical frequencies," Byren enthuses. "It’s a very difficult job, and it was done successfully."
A true space-qualified laser, able to withstand the rigors of space for long periods, is another unanswered need. "Right now, there are some lasers in space, but typically lasers have problems in the absence of atmosphere and gravity, and in high radiation fields," Nieuwsma says. "Lasers that have been in space for NASA and others have had short lifetimes, shorter than desired."
"The lack of atmosphere is an issue because of potential for outgassing of contaminants. Radiation is an issue, and which orbital plane you’re in determines how much radiation the system has to withstand. And the fact that you can’t get up there and maintain a laser in space is a big deal," Byren admits, "it really has to be reliable and redundant in many ways."
Gravity is yet another challenge. "It is amazing how many subtle things depend on the presence of gravity," Nieuwsma says, "and you find out when you try and work without it."
