Strong gravitational lensing of gravitational waves in Einstein
  Telescope
  Gravitational wave experiments have entered a new stage which gets us closer
to the opening a new observational window on the Universe. In particular, the
Einstein Telescope (ET) is designed to have a fantastic sensitivity that will
provide with tens or hundreds of thousand NS-NS inspiral events per year up to
the redshift z = 2. Some of such events should be gravitationally lensed by
intervening galaxies. We explore the prospects of observing gravitationally
lensed inspiral NS-NS events in the Einstein telescope. Being conservative we
consider the lens population of elliptical galaxies. It turns out that
depending on the local insipral rate ET should detect from one per decade
detection in the pessimistic case to a tens of detections per year for the most
optimistic case. The detection of gravitationally lensed source in
gravitational wave detectors would be an invaluable source of information con-
cerning cosmography, complementary to standard ones (like supernovae or BAO)
independent of the local cosmic distance ladder calibrations.
