Application of light beams with non-zero angular momentum in optical study of micrometer-size aerosol particles

摘要

A geometrical optics consideration of the torque exerted on a particle by a light beam with an angular momentum is presented. The beam is modelled as a bundle of rays directed normally to the wave front and carrying the power proportional to the local value of the light intensity. A numerical code is developed to calculate the ray propagation through the refracting and absorbing particle of arbitrary convex shape, which is applied to evaluation of the beam angular momentum transformation during the light interaction with the particle. Calculated values of the mechanical reaction experienced by the particle are used for the estimation of its motion in the optical levitation trap. The possibility of regular and predictable particle behaviour, which allows studying complicated patterns of light scattering by means of a single fixed detector, is shown.