Improvements Bring Chemical Oxygen-Iodine Laser Closer To Market

"Unlike most lasers, COIL can be scaled to very high power levels, in excess of 40 kilowatts," said David Carroll, a research scientist in the department of aeronautical and astronautical engineering at the U. of I. "And because COIL's wavelength of 1.3 microns can be transmitted through fiber-optic cable with very little loss, this laser is extremely well suited for applications needing high power and remote fiber optic delivery."

One such application is the decommissioning and dismantling of old nuclear facilities, Carroll said. "Not only can COIL rapidly cut through many materials, including iron, stainless steel and concrete, but laser cutting minimizes dust and fumes, thus reducing costly waste disposal. The use of a remote fiber-delivered COIL cutting tool in contaminated areas would also lower the risks to workers."

COIL was developed at the U.S. Air Force Research Laboratory (Kirtland Air Force Base, N.M.). To help commercialize the technology, the Air Force funded a Small Business Technology Transfer program with the U. of I. and STI Optronics in Bellevue, Wash.

As part of the program, Carroll and his U. of I. colleagues -- Wayne Solomon and Lee Sentman, both professors of aeronautical and astronautical engineering, and graduate student Darren King -- assembled a two-kilowatt COIL on the U. of I. campus. "This test bed gave us the capability to investigate new components and design techniques," Carroll said.

First demonstrated in 1977, the COIL system uses a series of chemical reactions to obtain excited atoms (or molecules) for subsequent lasing. A nozzle and buffer gas bring the primary flow to the supersonic velocities essential for operation.

"Using helium as the buffer gas, the Air Force had demonstrated a peak chemical efficiency of 27 percent," Carroll said. "But helium is relatively expensive, so one major objective of our program was to demonstrate high chemical efficiencies using less costly nitrogen as the buffer gas."

By developing an innovative nozzle design that was optimized for nitrogen, the researchers achieved a chemical efficiency of 23 percent. The redesigned nozzle also significantly reduced the amount of buffer gas required, further reducing the operating costs for a commercial COIL.

In addition to dismantling nuclear reactor facilities, COIL could be used in many other industrial applications, including shipbuilding, automotive manufacturing and heavy machinery manufacturing.

"The remote, flexible fiber-cutting tool could also be used underwater to seal small leaks in hulls without expensive dry-docking," Carroll said.