Radially Polarized Light for Detection and Nanolocalization of Dielectric Particles on a Planar Substrate

A fast noninvasive method based on scattering from a focused radially polarized light to detect and localize subwavelength nanoparticles on a substrate is presented. The technique relies on polarization matching in the far field between scattered and spurious reflected fields. Results show a localization uncertainty of $\approx {10}^{-4}{\lambda }^2$ is possible for a particle of area $\approx {\lambda }^2/16$. The effect of simple pupil shaping is also shown.