  The H.E.S.S. experiment in Namibia, Africa, is a high energy gamma ray tele-
scope sensitive in the energy range from 100 Gev to a few tens of TeV, via the
use of the atmospheric Cherenkov technique. To minimize the systematic errors
on the derived fluxes of the measured sources, one has to calculate the impact
of the atmospheric properties, in particular the extinction parameter of the
Cherenkov light ( 300-650 nm) exploited to observe and reconstruct atmospheric
particle showers initiated by gamma-ray photons. A lidar can provide this kind
of information for some given wavelengths within this range. In this paper we
report on the hardware components, operation and data acquisition of such a
system installed at the H.E.S.S. site.
