  Unlike normal fluorescent methods that use the intensity as a direct
measurement of the localized enhanced field, we use blinking statistics of
quantum dots (QDs). We have already shown that blinking gives a more accurate
characterization of the near-field. When an emitter is situated close to a
metallic surface, non-radiative pathways are opened up, leading to quenching of
the exciton. Blinking statistics, however, is only minimally affected by
quenching, and therefore can be used to probe emitters in close proximity to
metallic surfaces. We have expanded our method (COFIBINS) to high densities
using superresolution technique SOFI. A proof of principle for SOFI-COFIBINS is
demonstrated with a defocused point spread function. The method is then applied
to surface plasmon polaritons. SOFI-COFIBINS shows excellent agreement with the
average fluorescence intensity.
