Simonds, B.
, Rogers, K.
, Schulze, S.
, Newell, D.
, Shaw, G.
and Williams, P.
(2024),
Direct Realization of the Optical Watt from Planck's Constant, Metrologia, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956950
(Accessed April 22, 2025)
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Direct Realization of the Optical Watt from Planck's Constant
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Abstract
A primary force standard is implemented to directly realize Planck's constant to the optical Watt by means of radiation pressure at the kilowatt level. The high amplification laser-pressure optic, or HALO, is a multiple reflection radiation pressure apparatus used for absolute radiometry of high-power lasers. In this work, a primary standard electrostatic force balance is used to measure the reflection-enhanced optical forces. With this configuration, the HALO is used to measure laser powers in the range of 100 W to 5000 W from a 1070 nm fiber laser. The expanded uncertainty of the 5-kW measurement is 0.12%, which is both the lowest uncertainty multi-kW and radiation pressure based measurement to-date. The HALO result was validated against a thermal primary standard using a calibrated transfer standard. The degree of equivalence is 0.78% ± 1.12%, which demonstrates agreement within the uncertainties of these two primary standards.Citation
Metrologia
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Created October 28, 2024, Updated February 20, 2025