Photon momentum
Light carries a measurable push.
Radiation-pressure measurements connect optical power to force. They supply a benchmark for instrument qualification and a physically explicit starting point for propulsion.
Can the instrument recover the force predicted from intercepted or emitted power?
Use of radiation pressure for measurement of high-power laser emission
Demonstrates measuring optical power through the mechanical force exerted by laser radiation. Photon momentum is a real force source and an essential calibration and background term for proposed field-propulsion experiments.
Direct radiation pressure measurements for lightsail membranes
The authors characterize a microscopic, 50 nm silicon-nitride membrane with compliant supports, reporting radiation-pressure forces of 70 fN with an incident beam intensity of 110 W/cm². Their method jointly studies optical force, heating, incidence angle, beam size, and in-plane motion, supplying an unusually relevant example of how to separate coupled effects experimentally.
Axial force radiometer for primary standard laser power measurements using photon momentum
NIST describes a radiometer that infers laser power from the force carried by photons while allowing the beam to continue along a collinear path. Its comparison against an existing primary standard and explicit expanded-uncertainty budget illustrate how a small force becomes a defensible quantitative result.
Experimental demonstration of optical transport, sorting and self-arrangement using a ‘tractor beam’
Demonstrates optical pulling of spherical microparticles against the beam's forward direction and controlled particle sorting through polarization changes. Self-arranged particle structures further modify the optical force, giving a concrete example of geometry changing transport under an applied field.
Observation of a single-beam gradient force optical trap for dielectric particles
Demonstrates trapping of dielectric particles in water with the gradient force from a single focused laser beam, over reported sizes from roughly 25 nm to 10 μm. It provides a measured foundation for positioning and manipulating matter through engineered optical fields.
A new, lower value of total solar irradiance: Evidence and climate significance
Reports a total solar irradiance estimate of 1360.8 ± 0.5 W/m² for the 2008 solar minimum using SORCE/TIM measurements and radiometric tests. The solar-sail calculator uses 1361 W/m² as a rounded engineering reference at one astronomical unit.
Practical realization of the watt from Planck’s constant using radiation pressure
Combines repeated optical reflections with a primary electrostatic force balance to measure laser power. Its uncertainty budget separates noise, alignment and calibration effects; before-and-after measurements and an ABA analysis address drift.
Self-stabilizing photonic levitation and propulsion of nanostructured macroscopic objects
Identifies scattering patterns that can provide restoring forces and torques when an illuminated structure moves away from alignment. It connects nanoscale optical design to a macroscopic stability calculation.
Microscopic metavehicles powered and steered by embedded optical metasurfaces
Demonstrates optically driven microscopic vehicles whose metasurfaces redirect light. Polarization changes steer their trajectories, and the devices move microscopic cargo. This is a tangible example of geometry controlling motion through a specified external momentum source.