Direct Realization of the Optical Watt from Planck's Constant

Published

October 28, 2024

Author(s)

Brian Simonds, Kyle Rogers, Sven Schulze, David Newell, Gordon Shaw, Paul A. Williams

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

Pub Type

Journals

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Citation

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 2, 2025)