title: High-precision measurements of light-induced torque on absorbing microspheres.
abstract: Laser beams have been demonstrated to be capable of exerting torque as well as forces on microparticles. Using a custom magneto-optic manipulator, we directly measured the torque exerted by laser light on absorbing microspheres as a result of the transfer of spin angular momentum. A general method for measuring torque has been developed, and the experimental apparatus has shown a sensitivity of approximately 1 pN/nm.
authors.affiliation: European Laboratory for Nonlinear Spectroscopy, Università degli Studi di Firenze, Via N. Carrara 1, 1-50019 Sesto Fiorentino (Florence), Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Capitanio
authors.forename: Davide
authors.initials: D
authors.lastname: Normanno
authors.forename: Francesco Saverio
authors.initials: FS
authors.lastname: Pavone