In the framework of the studies related to the European Extremely Large Telescope (E-ELT), a fundamental importance
must be given to Sodium Laser Guide Stars (LGS) Wavefront Sensing which is essential to permit wide correction
uniformity and a relevant sky coverage. The finite distance of the sodium layer where the LGSs form, its width and
density time variability, requires detailed studies in order to better perform the wavefront measurement. Many LGS
peculiar problems, such as perspective elongation, focus uncertainty and launching angle , that can be neglected or more
easily managed for 8m class telescopes, become fundamental issues in the design of future LGS Wave-Front Sensors
(WFSs) for the E-ELT. In this paper we present the LGS WFS prototype built at the Osservatorio Astronomico di
Bologna reproducing the expected conditions of a E-ELT like LGS Shack-Hartmann WFS. The main scope of the
prototype is to cross check the simulations concerning the centroiding algorithms in the case of elongated spots using
different light intensities, pixel scales, spot offsets, sub-aperture Field of Views and elongated source intensity profiles.
Starting from the conceptual idea we show the system design and the integration in the lab. Finally the prototype optical
quality and its capability to perform the required tests are presented.