Optical pressure and numerical simulation of optical forces

Optical forces on a particle can be calculated using numerical methods and by integrating the Maxwell stress tensor over the surface of the particle. It is shown that this gives considerable numerical noise for the radiation force on particles with refractive index close to that of the surrounding medium and that a large number of mesh elements are necessary. It is found preferable to calculate the force from the local optical pressure, as this gives considerably less noise and requires significantly fewer mesh elements. Results are also compared with an analytical model based on Mie theory.