A laser surveying instrument, comprising a rotating unit for projecting a laser beam by rotary irradiation, a main unit for rotatably supporting the rotating unit, and a sealing means for sealing between the rotating unit and the main unit, wherein the sealing means comprises annular ridges formed on...http://www.google.es/patents/US7520064?utm_source=gb-gplus-sharePatente US7520064 - Laser surveying instrument
