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

A curved and one-sidedly open waveguide for simultaneous laser transmission welding in which the waveguide forms the last part along a path of laser light before the laser light enters a transmission component, the waveguide comprising:

• a first reflecting element having a reflecting surface capable of reflecting laser light, wherein
• the reflecting surface defines a receiving end of the waveguide at which laser light from a light guide or plurality of light guides as a laser light source is receivable, and an output end of the waveguide at which laser light is directable into a laser light transmitting work piece,
• the reflecting surface being defined by a curve between the receiving end and the output end wherein the reflecting surface of the first reflecting element has a continuously curved concave shape when viewed in cross-section, and
• wherein the first reflecting element is not opposed by a second reflecting element such that the waveguide is open in a direction normal to the reflecting surface, wherein
• the waveguide homogenizes the laser light from the laser light source, and
• the output end of the waveguide is adapted to a desired seam contour of the components to be welded such that the entire seam contour is irradiatable at the same time.