Optical Levitation by Radiation Pressure

Abstract

The stable levitation of small transparent glass spheres by the forces of radiation pressure has been demonstrated experimentally in air and vacuum down to pressures ∼1 Torr. A single vertically directed focused TEM₀₀‐mode cw laser beam of ∼250 mW is sufficient to support stably a ∼20‐μ glass sphere. The restoring forces acting on a particle trapped in an optical potential well were probed optically by a second laser beam. At low pressures, effects arising from residual radiometric forces were seen. Possible applications are mentioned.