Abstract: A system is disclosed for controlling the plane of a laser beam in either horizontal, vertical or selected grade angle attitudes. The system includes an assembly comprising a housing which carries the operative components in a water-tight enclosure. The laser beam is generated by a laser tube carried on a chassis which is mounted for a limited range of universal movement about orthogonally intersecting Y and X axes by means of a gimbal frame. Optics structure is provided to route the beam in a collimated path along a Z-axis longitudinally of the chassis. A beam reflector unit rotatably mounted on an end of the chassis reflects the beam in a plane orthogonal to the Z-axis through a lighthouse structure provided in an end of the housing. The system for controlling the beam plane attitude includes three level sensing vials which are carried on the chassis, as well as a pair of Y- and X-axis motors and associated drive trains.