SBIR-STTR Award

Current laser metal processing applications in the shipbuilding industry are limited by several factors. Commercial Nd:YAG systems only deliver power up to about 4 kW, and work at a wavelength that requires class A eye protection enclosures. These conditions severely limit Nd:YAG laser use in shipbuilding, since it deals with thicker steel and production operations that are performed on large components that are impractical to fully enclose. CO2 lasers operate at an eye-safe wavelength. However, the absence of a commercial fiber at this wavelength, along with some other factors, has limited CO2 lasers to hard optic systems. This requirement has resulted in CO2 lasers being limited to large gantry style systems with a complex series of bend mirrors. Recent developments in optics have produced new concepts that will allow transmission of relatively high power CO2 laser beams through flexible fibers. High-power beam delivery has been shown to be feasible theoretically. Hollow, flexible photonic bandgap fibers (OmniGuide PBFs) for guiding low power CO2 beams have recently been produced and tested (Nature, Vol. 420, p. 650, 2002). We propose developing OmniGuide PBF to efficiently guide multi-kW CO2 laser beams for power delivery in laser processing applications for shipbuilding. Our solution will reduce cost, simplify maintenance and increase the flexibility of laser systems. Benefits The ability to deliver CO2 laser power through a fiber greatly expands the possibilities for laser applications in shipbuilding and other applications. The fiber delivery mechanism will allow existing NC or semi-automatic cutting and welding systems to be easily retrofit with laser capabilities. In metal welding applications, the fiber will facilitate the use of CO2 lasers rather than more expensive Nd:YAG lasers. Both the operating and capital costs of CO2 lasers are 50% below the costs for Nd:YAG lasers at any given output power; furthermore, the eye-safe CO2 laser wavelength reduces the cost for full safety enclosure of Nd:YAG laser stations. The only reason for the success of Nd:YAG lasers in the marketplace is the availability of fiber beam delivery. CO2 lasers with fiber beam delivery should thus be the technology of choice for metal welding, assuming fiber costs are reasonably close to those for Nd:YAG fibers. In sheet metal cutting applications, a fiber will reduce the cost of the CO2 laser beam delivery system and therefore allow simplified and cheaper system designs. The savings should be up to 25% on a typical system. Keywords CO2 laser, optical fiber , metal cutting, photonic bandgap, shipbuilding, metal welding, materials processing

The objective of this SBIR Phase II project is to develop a fiber optic cable subsystem for high-power CO2 laser beam delivery. The design is based on OmniGuide's hollow-core photonic bandgap fiber technology. It will provide high power transmission through a compact, flexible fiber medium that will be relatively inexpensive thanks to a scalable manufacturing process. The technology will be installed in a thick-plate laser cutting system at Bender Shipbuilding & Repair Co. The system will utilize the laser-assisted oxygen cutting process (LASOX), which achieves thick plate cutting at power levels below 2 kW.

Keywords:
OPTICAL FIBER, CO2 LASER, HIGH-POWER LASER, PHOTONIC BANDGAP, MATERIALS PROCESSING