Air Force seeks to develop phased-array lasers for weapons and communications

Nov. 1, 2004
U.S. military researchers are looking into ways of steering laser beams from flat arrays of optical emitters...

WRIGHT-PATTERSON AFB, Ohio - U.S. military researchers are looking into ways of steering laser beams from flat arrays of optical emitters, in much the same way that phased-array radar systems steer radar beams without the need of a rotating platform.

Potential applications of this steerable laser technology include laser weapons, laser targeting and sensing, laser communications, and laser countermeasures.

In charge of the project are scientists at the U.S. Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, and the Defense Advanced Research Projects Agency (DARPA) Microsystems Technology Office in Arlington, Va. Scientists from these organizations say they are interested primarily in light wavelengths of 1.5 and 1 micron.

Air Force officials mandate that any technical ­approach related to this program must compensate for atmospheric effects. Different temperatures of the ­atmosphere can bend and change the phase of lasers, which without compensation can cause blurring.

The Air Force’s Airborne Laser, for example, uses adaptive optics, low-power laser sensors, and sophisticated signal processing to keep the weapons-grade laser in focus and on target. The Airborne Laser is designed to disable ballistic missiles in flight.

Air Force and DARPA experts at this initial stage are merely asking industry for information on adaptive photonic phase-locked elements and related technologies necessary to build an array of subapertures capable of transmitting, receiving, and rapidly steering spatially phased optical energy and images, in which each aperture should be transmissive.

Nevertheless, government scientists say they envision a two- or three-phase research and development program. The first phase, they say, would last for one year, and the total duration of the program could be as long as five years.

The potential phase-one goal is to develop transmissive optical phased-array subaperture elements of two centimeters or larger. Nonmechanical beam steering should be continuous to at least 20 degrees in any direction, covering a field of regard of at least 40 degrees. In the first phase, participating organizations should demonstrate computer algorithms that help the laser compensate for atmospheric distortion.

The final one or two phases of the program would demonstrate a half-meter array of subapertures using no more than 100 subapertures, which would compensate for atmospheric effects in real time. This technology should scale to at least 100 kilowatts for weapons, and one or more kilowatts for sensors.

Steering should be faster than one millisecond from any location in the field of interest to any other location.

Air Force and DARPA officials are setting high standards for any company ultimately selected to participate in this program - if the program goes forward.

Those who would like to participate not only need to have deep technological expertise in steerable lasers, but they also must have security clearances and secure facilities.

According to a request for information released in September, interested parties “should have documented expertise and existing capability in the design, development, and production of optical phased-array beam steering, phased lasers, subaperture receive technologies, atmospheric compensation techniques, and/or the integrations of these technologies, and should identify their interest and capability to respond to the requirement ­including their capability to manufacture and commercialize the end-product.”

The request goes on, “a security clearance will be ­required. Interested parties must maintain, or have the ability to provide, secure facilities and possess, or have the ability to obtain, a U.S. Secret level security clearance.”

Although the deadline for submitting a formal ­response to the request for information has passed, more information on the program is available from Dr. Paul F. McManamon of the Air Force Research Lab at Wright-Patterson Air Force Base. His phone number is 937-255-4039 ext. 4024. The federal solicitation number for the request for information was RFI-04-PKDA-APPLE.

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