Position measurement of a levitated particle with vectorial light
We develop a fully vectorial, semiclassical scattering formalism for optically levitated dipolar scatterers, expressed within the angular spectrum representation and applicable to arbitrary trapping-field configurations as well as to high--numerical-aperture focusing. Within this framework, we introduce the information radiation pattern to characterize the angular distribution of position-dependent information and use a Richards--Wolf projection of the scattered field onto the local-oscillator mode to quantify the resulting mode-matching efficiency, yielding experimentally realistic forward- and backward-detection efficiencies. As a worked example, we apply the formalism to a radially polarized trapping beam and confirm that the axial recoil heating rate is reduced relative to a conventional linearly polarized Gaussian tweezer. The theoretical framework is implemented in LevitationToolbox, an open-source Python package intended to support the design and optimization of near-Heisenberg-limited levitated optomechanical experiments.