Researchers at the National Institute of Standards and Technology (NIST) have been developing a novel way of measuring laser power. Their device, called the Radiation Pressure Power Meter (RPPM), makes its measurements using the force exerted by the laser light itself.

The NIST team has now fully tested this instrument at the highest power to date—50 kilowatts (kW)—using a laser at the High Energy Laser Systems Test Facility (HELSTF), operated by the U.S. Army and located in New Mexico. By comparison, a 5-kW laser beam can cut through an inch of steel.

“We don’t have tens of kilowatts of laser power at our disposal here at NIST,” says NIST physicist Joshua Hadler. “This was an opportunity to go at power levels that we’ve never got to before.”

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