Light Pressure on an Inhomogeneous Spherical Particle in the Field of Laser Tweezers

The light pressure on an inhomogeneous spherical dielectric particle consisting of a shell and a core with different refractive indices is considered. The forces acting on this particle in a laser beam with a Gaussian intensity profile have been found in the geometrical optics approximation. The radiation propagation is analyzed by taking into account the different refractive indices of the core, the shell, and the medium surrounding the particle. The light pressure is shown to depend significantly on the core radius, which allows the core size to be estimated from the spatial dynamics of the particle in the field of optical tweezers.