Waveguide for plastic welding, arrangement, and welding method with a waveguide, and manufacturing method of a waveguide

A method for plastic welding with an arrangement comprising:

• a laser light source, a light guide or a plurality of light guides, and a curved and one-sidedly open waveguide, wherein the one-sidedly open waveguide comprises a first reflecting element having a reflecting surface configured to reflect laser light, wherein the reflecting surface defines a receiving end at which laser light from the light guide or the plurality of light guides is receivable, and an output end at which laser light is directable into a laser light transmitting work piece, and the reflecting surface is defined by a curve between the receiving end and the output end so that the reflecting surface of the first reflecting element has a continuously curved concave shape when viewed in cross-section, and the first reflecting element is not opposed by a second reflecting element so that the one-sidedly open waveguide is open in a direction normal to the reflecting surface, wherein in during operation of the arrangement, the laser light passes from the laser light source through the light guide and is subsequently reflected at least once at the reflecting surface of the reflecting element of the one-sidedly open waveguide, wherein the method for plastic welding comprises the following steps:
• a) arranging two plastic components to be welded to each other in a mounting device;
• b) creating laser light by means of a laser light source, wherein the laser light passes through the light guide or the plurality of light guides, and is subsequently reflected at least once at the reflecting surface of the reflecting element of the one-sidedly open waveguide;
• and
• c) welding the plastic components to be welded to each other by means of the laser light reflected by the one-sidedly open waveguide.