  In recent years free-loating planets (FFPs) have drawn a great interest among
astrophysicists. Gravitational microlensing is a unique and exclusive method
for their investigation which may allow obtaining precious information about
their mass and spatial distribution. The planned Euclid space-based observatory
will be able to detect a substantial number of microlensing events caused by
FFPs towards the Galactic bulge. Making use of a synthetic population
algorithm, we investigate the possibility of detecting finite source effects in
simulated microlensing events due to FFPs. We find a significant efficiency for
finite source effect detection that turns out to be between 20% and 40% for a
FFP power law mass function index in the range [0.9, 1.6]. For many of such
events it will also be possible to measure the angular Einstein radius and
therefore constrain the lens physical parameters. These kinds of observations
will also offer a unique possibility to investigate the photosphere and
atmosphere of Galactic bulge stars.
