Abstract

The angular momentum carried by polarized light was first measured in 1936 by Richard Beth, who measured the tiny reaction torque due to the change in polarization of light on passage through a quartz wave plate. Using the modem single-beam gradient optical trap, we can observe the reaction torque on a birefringent particle on a microscopic scale, where the observable effects are several orders of magnitude greater.

© 1998 Optical Society of America