High-precision measurements of light-induced torque on absorbing microspheres.
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.
Capitanio
Marco
M
European Laboratory for Nonlinear Spectroscopy, Università degli Studi di Firenze, Via N. Carrara 1, 1-50019 Sesto Fiorentino (Florence), Italy.
Normanno
Davide
D
Pavone
Francesco Saverio
FS