By John Keller
WRIGHT-PATTERSON AFB, Ohio, 8 March 2006. Researchers at the Raytheon Co. Electronic Systems division in Marlborough, Mass., are designing a coherently phased array of optical apertures for new high-power laser systems.
Raytheon won a $5.8 million contract March 7 for the Adaptive Photonic Phase-Locked Elements (APPLE) program to build an array of sub-apertures capable of transmitting and rapidly steering spatially phased optical energy and images in which each sub-aperture should be transmissive.
Awarding the contract are officials of the U.S. Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio. The APPLE project is under supervision of the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va.
Under terms of this contract, Raytheon scientists will attempt to verify that the proposed APPLE vision is compatible with high-power laser operation. The contract number is FA8650-05-C-7211. Work is to be finished in March 2007.
The APPLE program is to enable all-electronic combining of high-power laser beams within an agile, conformal aperture -- a practical approach to synthesizing high-power weapon lasers from low-power modules for applications such as laser radar, laser target designation, laser communications, and weapons-grade lasers, DARPA officials say.
The idea is to provide electro-optical systems with the same mission flexibility and performance that microwave phased arrays provide for RF applications such as radar and electronic warfare systems.
APPLE seeks to develop a modular, phase-locked, coherently combined laser system that can be electronically steered to large angles, while automatically compensating for optical aberrations from atmospheric turbulence and thermal aberrations within the beam director.
The modular feature enables the coherent combining of several optical apertures to create a transmit/receive array of arbitrary size, similar to how RF phased array antennas scale up by adding RF receive/transmit modules.
The resulting high-power laser systems made from low-power modules would leapfrog bottlenecks to create ever-higher-power monolithic laser systems. The program initially focuses on developing a 2.5-centimeter aperture at 100 Watts. More information is available online at www.darpa.mil/mto/apple.