Effect of spatial coherence on radiation forces acting on a Rayleigh dielectric sphere

We show that the radiation forces (RFs) on a Rayleigh dielectric sphere induced by a partially coherent light beam are greatly affected by the spatial coherence. We find that the magnitude of the RFs greatly decreases as the spatial coherence decreases and derive an inequality for the required correlation width sigma(0) (i.e., the spatial coherence of the beam) to stably trap the particles. (c) 2007 Optical Society of America