A guiding assembly for a riser piping system in an opening in the bottom of a floating structure, said assembly permitting limited axial and angular displacement of the riser piping system in said opening. A laser oscillating apparatus is designed to excite a laser gas in a laser tube by introducing electromagnetic waves into the laser tube through a plurality of slots formed in a waveguide wall and generate a laser beam by resonating the light generated from the laser gas. The electric motor including a rotor and a stator, wherein a position of the stator within the housing is maintained by a retainer removeably disposed between the stator and the housing.