The U.S. military can now calibrate high-power laser systems, such as those intended to defuse unexploded mines, more quickly and easily thanks to a novel nanotubecoated power measurement device developed at the National Institute of Standards and Technology (NIST).
The new laser power meter, tested at a U.S. Air Force base last week, will be used to measure the light emitted by 10-kilowatt (kW) laser systems. Light focused from a 10-kW laser is more than a million times more intense than sunlight reaching the Earth. Until now, NIST-built power meters, just like the lasers they were intended to measure, were barely portable and operated slowly. The new power meter is much smaller—about the size of a crockpot rather than a refrigerator. It also features a new design that enables it to make continuous power measurements.
A key innovation is the use of a sprayed-on coating of carbon nanotubes—tiny cylinders made of carbon atoms—which conduct heat hundreds of times better than conventional detector coating materials.
In the new power meter, laser light is absorbed in a coneshaped copper cavity, where a spinning mirror directs the light over a large area and distributes the heat uniformly. The cavity is lined with a NIST-developed coating made of multiwalled carbon nanotubes held together by a potassium silicate (water glass) binder, and surrounded by a water jacket. The coating absorbs light and converts it to heat. The resulting rise in water temperature generates a current, which is measured to determine the power of the laser.
More info: Laura Ost, laura.ost@nist.gov, 303-497-4880
