Stabilizing Design for Laser Pushed Light Sails

$100 million has been put into the Breakthrough Starshot project to push a sail up to 20% the speed of light and send an unmanned probe to Alpha Centauri in about 20 years. There is progress on a stabilizing design for a sail to ride the laser beam.

An optical beam rider making use of a light sail comprising two opposing diffraction gratings is experimentally demonstrated for the first time. We verify that the illuminated space-variant grating structure provides an optical restoring force, exhibiting stable oscillations when the bigrating is displaced from equilibrium. We further demonstrate parametric cooling by illuminating the sail with synchronized light pulses. This experiment enhances the technical feasibility of a laser-driven light sail based on diffractive radiation pressure.

Physical Review Letters – Experimental Verification of a Bigrating Beam Rider