Detection of thermal degradation at the beam entry surface of a component during laser welding of plastics involves forming image of beam entry point at radiation detector screened from the laser beam

摘要

Areas of the beam entry surface(2) on one(5) of the components(3,5) to be welded are optically reproduced on a radiation detector(10) which detects wavelengths of 300-1200nm. The radiation detector is screened from radiation produced by the welding laser(15) by one or more optical components(13,14) which allow transmission of specific wavelengths. An independent claim is included for the process equipment in which the optical axis of the laser welding beam, at least over part of its length, coincides with the optical axis of an image of the beam entry area to the laser transmitting component(5) reproduced at the radiation detector(10). Alternatively the optical axis of the laser welding beam at the entry point to the laser transmitting component intersects the optical axis of the image of this surface at the radiation detector.