  We report on direct imaging of vortex matter nucleated in micron-sized
Bi2Sr2CaCu2O8+y superconducting samples that incidentally present a bridge
structure. We find that when nucleating vortices in a field-cooling condition
the deck of the bridge acts as a converging lens for vortices. By means of
Bitter decoration images allowing us to quantify the enhancement of
vortex-vortex interaction energy per unit length in the deck of the bridge, we
are able to estimate that the deck is thinner than 0.6\,$\mu$m. We show that
the structural properties of vortex matter nucleated in micron-sized thin
samples are not significantly affected by sample-thickness variations of the
order of half a micron, an important information for type-II
superconductors-based mesoscopic technological devices.

Superconductivity;Soft Condensed Matter