Light’s force needs a quieter room
HALO measures power through pressure.
- Event / announcement date
- 2026-01-22
In its January 22, 2026 HALO account, NIST described a prototype disturbance attributed to air from hallway doors reaching the laboratory through ventilation. That explanation remained a hypothesis; the apparatus and lab were modified. A stronger signal still required control of its surroundings. [1]
The instrument measures light through momentum. NIST’s project description explains that reflection exerts force without substantially consuming the beam’s energy. Redirecting the light onto a sensing mirror repeatedly strengthens the force signal. That offers a route around the difficulty of scaling sensitive, heat-based measurements from very weak light to kilowatt beams. [2]
The result predates the spotlight. A 2021 paper reported 95%-confidence expanded uncertainties of 0.26% at 10 kilowatts and 0.46% at one kilowatt. The measurements linked power to the SI kilogram through force. Those figures describe that experiment, rather than a guarantee for every installation. [3]
For manufacturing, delivered power is only part of process control. NIST also studies beam quality and the interaction between light and materials. [4]
Absorption depends on material, surface finish and incoming power. Calibration schedules, laser degradation and measurement procedures also affect delivery in metal additive manufacturing, the program explains. A detector specification alone cannot establish consistent production. [4]
The source
- National Institute of Standards and Technology: Spotlight: Scientists Can Measure Laser Power Using HALO ↗
Source date 2026-01-22 · reviewed October 29, 2026 - National Institute of Standards and Technology: High Amplification Laser-pressure Optic (HALO) ↗
Source date 2023-04-06 · reviewed October 29, 2026 - National Institute of Standards and Technology: High amplification laser-pressure optic enables ultra-low uncertainty measurements of optical laser power at kilowatt levels ↗
Source date 2021-10-15 · reviewed October 29, 2026 - National Institute of Standards and Technology: High-Power Laser Applications ↗
Source created 2015-11-10 · reviewed October 29, 2026 · Created November 10, 2015.
About this item: Retrospective report. No first-hand reporting or independent testing is claimed. Corrections policy.
