DARPA evaluates Excalibur programme prototype

10 March 2014 (Last Updated March 10th, 2014 18:30)

The US Defense Advanced Research Projects Agency (DARPA) has successfully developed and tested a 21-element optical phased array (OPA), as part of its Excalibur programme.

DARPA laser

The US Defense Advanced Research Projects Agency (DARPA) has successfully developed and tested a 21-element optical phased array (OPA), as part of its Excalibur programme.

The OPA features three identical clusters of seven tightly packed fibre lasers, with each cluster only 10cm across. It was able to precisely hit a target located more than four miles away.

DARPA programme manager Joseph Mangano said: "The success of this real-world test provides evidence of how far OPA lasers could surpass legacy lasers with conventional optics.

"DARPA is planning tests over the next three years to demonstrate capabilities at increasing power levels, ultimately up to 100kW; power levels otherwise difficult to achieve in such a small package."

The demonstrations also demonstrated near-perfect correction of atmospheric turbulence at levels well above that possible with legacy optics using an ultra-fast optimisation algorithm, and then correcting the resulting static optically aberrated atmosphere in sub-milliseconds to maximise the laser irradiance delivered to the target.

The experiments were conducted several tens of metres above the ground, where atmospheric effects can be most detrimental for the Army, Navy and Marine Corp applications.

In addition, the demonstration helps advance Excalibur's goal of developing a 100kW-class laser system in a scalable, ultra-low size, weight and power requirements (SWaP) OPA configuration compatible with current weapon system platforms.

"This technology may also benefit low-power applications such as laser communications."

Mangano said the systems can achieve the ultra-low SWaP required for deployment on a broad spectrum of platforms due to power efficiencies of more than 35% and the near-perfect beam quality of fibre laser arrays.

"Beyond laser weapons, this technology may also benefit low-power applications such as laser communications and the search for, and identification of, targets."

Additional tests are scheduled to be conducted in future to prove the OPA's capabilities in even more intense environmental turbulence conditions and at higher powers, which are likely to offer improved reliability and performance for aircraft self-defence and ballistic missile defence applications.


Image: The optical phased array (OPA) prototype used in the Excalibur demonstration. Photo: DARPA.

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