Optical forces on particles of arbitrary shape and size

In this paper we present a theory of optical forces on particles of arbitrary shape and size and with fields of arbitrary spatial profiles. This means the theory applies to particle-light interactions in every optical regime: Rayleigh, Mie and geometrical. The theory has the advantage of conceptual simplicity and can handle the real, focused Gaussian beams typically found in optical tweezer experiments. We present optical force calculations on spheres and cubes, and the results obtained with our theory agree well with benchmark calculations obtained using other techniques.