Three-dimensional, arbitrary orientation of focal polarization

We demonstrate a simple setup for generating a three-dimensional arbitrary orientation of the polarization vector in a laser focus. The key component is the superposition of a linearly and a radially polarized laser beam, which both can be controlled individually in intensity and relative phase. We exemplify the usefulness of this setup by determining the spatial orientation of a single silver nanorod in three-dimensional space by recording the angle-variable backscattered light intensity.