Measurement of optical binding force between two colloidal particles

Optical binding has been proposed to be responsible for the cluster formation of micron size dielectric spheres in coherent light fields. However, a direct measurement of the forces involved in binding is missing. We report an experimental study of optical binding forces between two optically trapped dielectric spheres. Results for optical forces are presented as a function of three parameters: inter particle separation, particle size, and respective polarizations. A comprehensive calculation based on the generalized Mie scattering theory for the experiment has also been conducted. This paper will present a comparison between experimental and theoretical results.