Programmable vector point-spread function engineering.

We use two nematic liquid crystal spatial light modulators (SLM's) to control the vector point spread function (VPSF) of a 1.3 numerical aperture (NA) microscope objective. This is achieved by controlling the polarization and relative phase of the electric field in the objective's pupil. We measure the resulting VPSF's for several different pupil field polarization states. By using single fluorescent molecules as local field probes, we are able to map out the focal field distributions and polarization purity of the synthesized fields. We report the achieved field purity and address the experimental issues that currently limit it.