A non-cylindrically surfaced lens converts a collimated light beam into a light plane that increases a light intensity toward distal portions of the light plane's arc so as to substantially uniformly project a reference light line onto a reference surface onto which the light plane is projected. The...http://www.google.es/patents/US7520062?utm_source=gb-gplus-sharePatente US7520062 - Light-plane projecting apparatus and lens
