  When subjected to monochromatic incident light a nanoparticle will emit light
which then interferes with the incident beam. With sufficient contrast and
sufficiently close to the particle this interference pattern may be recorded
with a pointed optical fiber in collection mode. It is shown that the analytic
dipole model accurately reproduces the observed interference pattern. Using
this model and measuring only the lengths of the first two major axes of the
observed elliptical fringes we are able to reproduce and quantify the fringe
pattern. Importantly, we are able to locate the nanoparticle, with respect to
the fibre, using only visible light in a simple experimental setup. For the
case described where the image plane is of the order microns above the
substrate, hence the fringe number is large, it is shown that the prediction
for the particle location and fringe number is insensitive to measurement
errors. The phase shift of the scattered wave, a quantity that is notoriously
difficult to measure, is easily determined from the theory however it is very
sensitive to errors.
