Monitoring laser beam working process - by measuring intensity changes in measuring laser beam after passage through vapour or plasma cloud above work area

摘要

Method of monitoring the quality of a laser beam working process consists of monitoring changes in the vapour or plasma cloud (12) above the working area using a measuring laser beam (18) which has the same or similar wave length to that of the working laser but a lower power. The measuring beam is directed through the cloud (12) in a direction perpendicular to that of the working laser beam and/or parallel to surface of the workpiece. Variations in the intensity of the measuring beam after passing through the cloud are used to indicate change in process conditions and a process parameter is changed in accordance with the variation. USE/ADVANTAGE - Laser welding using CO2; Nd:YAG; and excimer lasers. Monitors the amount of laser radiation which is absorbed and dispersed by the cloud and changes certain parameter to ensure that the correct amt. of radiation is transferred to the workpiece.