Method and apparatus for heating plastics by means of laser beams

A method for welding plastic comprising the steps of:

• providing a laser beam source for producing a laser beam;
• locating a lens downstream of the last beam source for collimating the laser beam;
• splitting the collimated laser beam into a plurality of beams by means of a multiple wedge plate comprising a plurality of wedges which correspond to a desired number of laser points to be produced, wherein the wedges are offset from horizontal at a desired angle;
• varying the direction of the plurality of beams treading out of the multiple wedge plate by a movable deflecting element located downstream of the splitting means comprising at least one deflecting wedge, wherein the plurality of beams are fed through the deflecting wedge, said deflection wedge running with its contact edges parallel to contact edges of the multiple wedge plate splitting the laser beam;
• moving the deflecting element continuously to and fro transversely to the optical axis of the beam path of the plurality of laser beams for directing the plurality of laser beams simultaneously to various points on a focal plane of plastics to be welded;
• locating a converging lens downstream of the movable deflecting element, wherein the plurality of beams deflected by the deflecting wedge of the deflecting element are fed through the converging lens and continue to be collimated thereby to produce a plurality of laser points on a focal plane of plastic to be welded;
• and
• providing a movable transparent ball downstream of the converging lens wherein the plurality of laser beams are coupled and guided over the focal plane during movement of the ball for welding the plastic.