The team of Christopher Cromer, John Lehman and Xiaoyu Li are recognized for establishing traceability of multi-kilowatt laser power to fundamental units in support of laser manufacturing and military applications. This accomplishment was the result of a lengthy innovative research program in high power laser metrology leading to world class high power optical coatings and novel laser power meters capable of direct, accurate laser power measurements up to 100 kW.
The challenge of making accurate high power measurements for these applications is that a laser bright enough to cut steel will damage today's measurement equipment. New damage resistant materials and power meters were needed to characterize both laser beam quality and power. As a result of the Team's work, NIST is the only National Metrology Institute in the world that can accurately characterize common high power lasers for materials processing, which typically carry a price tag of $10k per 1 kW of power. Accurate laser power measurements, traceable to NIST, are a critical benchmark in this market because of their direct impact on pricing. Thanks to the team, these high power laser systems – such as those used in laser welding tools and those intended to defuse unexploded land mines – can now be characterized more quickly and easily using the innovative NIST power meter. The NIST power meter has several novel design features including a water-cooled cavity, world-record high damage threshold coating, in a package roughly one-fifth the size of existing standards in the 1 to 100 kilowatt laser power range. Furthermore, the new NIST power meter is capable of field measurements with a factor of two or more lower overall uncertainty and can be electrically-calibrated in the field, unlike previous, cumbersome standards that were developed at NIST in the 1970's.