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16 Apr 2012
Rofin-Sinar subsidiary awarded multiple contracts for kilowatt-class fiber amplifiers as part of directed energy weapons effort.
Nufern, the Rofin-Sinar subsidiary that specializes in fiber lasers and related technology, is expanding manufacturing operations at its Connecticut headquarters to fulfill multiple orders for the US military.
Following a number of awards on competitively bid programs, Nufern says that it will build 46 kilowatt-class compact fiber amplifiers, with delivery scheduled for later this year. The various awards represent multi-million dollar contracts and are part of the US military’s efforts to develop laser-based directed energy weapons capable of destroying both air and ground targets.
Following the recent demise of the Airborne Laser Test Bed, which was based on extremely bulky, hazardous and unreliable chemical lasers, much of that effort is now focused on fiber lasers and being co-ordinated through the Defense Advanced Research Project Agency (DARPA) “Excalibur” project.
With a provisional budget of $24 million in fiscal year 2012 and $25.8 million in 2013, Excalibur combines three laser-related projects, including the revolution in fiber lasers (RIFL) effort in which Nufern, Northrop Grumman and Fraunhofer USA were all involved.
The ultimate target for Excalibur, which is co-ordinated by DARPA project manager Joseph Mangano, is to develop high-power optical arrays that can be steered electronically, with each array based on a multi-kilowatt fiber laser amplifier. Those beams will also use adaptive optics technology – used today in both large telescopes and high-end ophthalmic imaging equipment – to maintain beam quality over large stand-off distances, where atmospheric turbulence is a factor.
UAV protection
Eventually, it is hoped, lightweight, compact and scalable laser arrays will be used to defend aircraft from future anti-aircraft missiles. In particular, low-flying unmanned aerial vehicles (UAVs) should benefit from being able to fly lower to the ground without being shot down, by using high-energy countermeasures. In its FY 2013 budget document, DARPA said:
“Excalibur will enable these reconnaissance platforms to fly at lower altitude and obtain truly persistent, all-weather ground reconnaissance despite low-lying cloud cover.”
One of the major technical challenges with a directed energy weapon based on multiple sources, and a key R&D topic right now, is the need to combine a large number of beams generated separately without losing the all-important beam quality that is necessary to maintain the laser’s effectiveness at remote distances.
Last year, project milestones achieved under Excalibur included the demonstration of 1.6 kW coherently combinable fiber laser amplifiers with an electrical efficiency of more than 30% and, says DARPA, “near-perfect” beam divergence of 1.2x diffraction-limited.
Target milestones
The Excalibur project partners are now working to increase that combinable power to 3 kW, with the aim of demonstrating the higher power level with a beam divergence of 1.4x diffraction-limited this year.
Other key targets for FY 2012 include combining five 100 W single-mode laser diode modules to produce a single 500 W output beam with an electrical efficiency in excess of 40%, and to begin developing other parts of the directed energy system, such as packaging, power storage and thermal management. Those developments are targeted towards a system weighing less than 5 kilograms per kilowatt of output power.
Scott Christensen, Nufern’s director of government, military and aerospace sales, said in the firm’s announcement of the contract wins:
“The award of these multi-million dollar contracts is a testament to the innovative abilities of our scientists, engineers, technicians, and other support staff that was crucial from conceptualization to productization stages and everything in between.”
“The entire Nufern team is pleased to be able to expand its fiber laser manufacturing operations here in East Granby to meet the volume demands of these critical programs,” added Christensen. He will also be chairing technical sessions on the development of fiber lasers for defense and security applications at next week’s SPIE Defense, Security and Sensing (DSS) conference and trade show, which is taking place in Baltimore, Maryland, for the first time.
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