Optical collection of multiple spheres in single tightly focused beams

The algorithm of multiple scattering is presented in this paper. The model of dynamic simulation and collision detection of multiple spheres is developed. The optical collection of multiple spheres in single tightly focused beams is simulated dynamically, considering the effects of Brownian motion of the spheres and the optical forces. The number of spheres with different parameters collected in a Gaussian beam is obtained using a program based on the T-matrix method and multiple scattering. Some interesting effects of the refractive index and size of spheres are revealed. The optical collection is explained physically in terms of optical binding. The method for modeling the collection of microspheres can be applied to the optical trapping and manipulation of multiple particles in general.