Multi-kilowatt cw laser power measurement comparison between national standards

PTB and NIST performed a comparison for high accuracy continuous wave optical power measurements in the kilowatt regime. The NIST carried out measurements with a power meter relying on photon momentum, while PTB performed the measurements with a modified off-the-shelf thermal power meter. The non-absorbing photon momentum measurement approach permits the two power meters to measure the same laser beam optical path simultaneously, resulting in a direct comparison of the meters supported by an optical system to accommodate differences in instrument settling times. The results show agreement within the expanded uncertainties for each instrument. NIST and PTB illustrate a degree of equivalence of 0.49% with an expanded uncertainty of 1.37% (k = 2) for an average result across all power levels.

Authors:  
Kyle Rogers¹, Paul Williams¹, Marcel Pastuschek², Holger Lecher², Stefan Kück²,
Marco López² and John Lehman¹

¹ Sources and Detectors Group, US National Institute of Standards and Technology, Boulder, CO, United States of America
² Optics Division, Physikalisch-Technische Bundesanstalt, Braunschweig, Germany

For further information:
Kyle Rogers et al, Metrologia 61 025006, 2024.  https://doi.org/10.1088/1681-7575/ad2538

Contact person:
Dr. Marco López
Email: marco.lopez(at)ptb