Tech

March 7, 2014

Excalibur prototype extends reach of high-energy lasers

darpa-laser
High-energy lasers have the potential to benefit a variety of military missions, particularly as weapons or as high-bandwidth communications devices.

However, the massive size, weight and power requirements of legacy laser systems limit their use on many military platforms.

Even if SWaP limitations can be overcome, turbulence manifested as density fluctuations in the atmosphere increase laser beam size at the target, further limiting laser target irradiance and effectiveness over long distances.

Recently, DARPA’s Excalibur program successfully developed and employed a 21-element optical phased array with each array element driven by fiber laser amplifiers. This low power array was used to precisely hit a target 7 kilometers—more than 4 miles away. The OPA used in these experiments consisted of three identical clusters of seven tightly packed fiber lasers, with each cluster only 10 centimeters across.

“The success of this real-world test provides evidence of how far OPA lasers could surpass legacy lasers with conventional optics,” said Joseph Mangano, DARPA program manager. “It also bolsters arguments for this technology’s scalability and its suitability for high-power testing. DARPA is planning tests over the next three years to demonstrate capabilities at increasing power levels, ultimately up to 100 kilowatts—power levels otherwise difficult to achieve in such a small package.”

In addition to scalability, Excalibur demonstrated near-perfect correction of atmospheric turbulence—at levels well above that possible with conventional optics. While not typically noticeable over short distances, the atmosphere contains turbulent density fluctuations that can increase the divergence and reduce the uniformity of laser beams, leading to diffuse, shifted and splotchy laser endpoints, resulting in less power on the target. The recent Excalibur demonstration used an ultra-fast optimization algorithm to effectively “freeze” the deeply turbulent atmosphere, and then correcting the resulting static optically aberrated atmosphere in sub-milliseconds to maximize the laser irradiance delivered to the target. These experiments validated that the OPA could actively correct for even severe atmospheric distortion. The demonstration ran several tens of meters above the ground, where atmospheric effects can be most detrimental for Army, Navy and Marine Corp applications. In addition, these experiments demonstrated that OPAs might be important for correcting for the effects of boundary layer turbulence around aircraft platforms carrying laser systems.

The successful demonstration helps advance Excalibur’s goal of a 100-kilowatt-class laser system in a scalable, ultra-low SWaP OPA configuration compatible with existing weapon system platforms. Continued development and testing of Excalibur fiber optic laser arrays may one day lead to multi-100 kilowatt-class HELs in a package 10 times lighter and more compact than legacy high-power laser systems. Future tests aim to prove the OPA’s capabilities in even more intense environmental turbulence conditions and at higher powers. Such advances may one day offer improved reliability and performance for applications such as aircraft self-defense and ballistic missile defense.

“With power efficiencies of more than 35 percent and the near-perfect beam quality of fiber laser arrays, these systems can achieve the ultra-low SWaP required for deployment on a broad spectrum of platforms,” said Mangano. “Beyond laser weapons, this technology may also benefit low-power applications such as laser communications and the search for, and identification of, targets.”




All of this week's top headlines to your email every Friday.


 
 

 
NASA photograph

NASA begins sixth year of airborne Antarctic ice change study

NASA photograph by Michael Studinger NASA’s DC-8 flying laboratory is shown in its parking spot on the ramp at the Aeropuerto Presidente Carlos Ibáñez del Campo in Punta Arenas, Chile, after its transit flight from NASA...
 
 
NASA photograph by Patrick Rogers

Scientific balloon launch highlights NASA exhibit at Balloon Fiesta

NASA photograph by Jay Levine Magdi Said, technology manager for NASA’s Scientific Balloon Program office at NASA’s Wallops Flight Facility, explains elements of NASA’s use of science balloons.   A live t...
 
 
NASA photograph by John Sonntag

Preparing for Antarctic flights in California desert

NASA photograph by John Sonntag The constellation Ursa Major looms over a GPS-equipped survey vehicle and a ground station to its left at El Mirage Dry Lake. By comparing elevation readings from both GPS sources, researchers ca...
 

 
NASA photograph by Tom Tschida

NASA-pioneered Automatic Ground-Collision Avoidance System operational

NASA photograph by Jim Ross The U.S. Air Force’s F-16D Automatic Collision Avoidance Technology (ACAT) test aircraft banks over NASA’s Dryden (now Armstrong) Flight Research Center during a March 2009 flight.  ...
 
 
USF/WHOI/MBARI/NASA image

U.S. initiates prototype system to gauge national marine biodiversity

USF/WHOI/MBARI/NASA image NASA satellite data of the marine environment will be used in prototype marine biodiversity observation networks to be established in four U.S. locations, including the Florida Keys, pictured here. The...
 
 
NASA photograph by David C. Bowman

NASA helicopter test a smashing success

NASA photograph by David C. Bowman Technicians at NASA Langley pulled a helicopter 30 feet into the air before dropping it to test crashworthy systems.   The successful crash test of a former Marine helicopter could help l...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>