  Interferometric observations of microlensing events have the potential to
provide unique constraints on the physical properties of the lensing systems.
In this work, we first present a formalism that closely combines
interferometric and microlensing observable quantities, which lead us to define
an original microlensing (u,v) plane. We run simulations of long-baseline
interferometric observations and photometric light curves to decide which
observational strategy is required to obtain a precise measurement on vector
Einstein radius. We finally perform a detailed analysis of the expected number
of targets in the light of new microlensing surveys (2011+) which currently
deliver 2000 alerts/year. We find that a few events are already at reach of
long baseline interferometers (CHARA, VLTI), and a rate of about 6 events/year
is expected with a limiting magnitude of K~10. This number would increase by an
order of magnitude by raising it to K~11. We thus expect that a new route for
characterizing microlensing events will be opened by the upcoming generations
of interferometers.
