REAL TIME CONTROL OF LASER BEAM CHARACTERISTICS IN A LASER-EQUIPED MACHINE TOOL

摘要

A method and apparatus for real time control of laser beam characteristics in a high power laser-equipped machine tool. A beam path inp ut signal is produced related to changes in the length of the laser beam path a s the processing head of the machine tool moves over the workpiece. An integrator produces a signal related to the real time changes in thermal loading of the laser output coupler as the laser beam is applied and as the output power level is adjusted. The beam path and thermal loading signals are used to drive a collimator so as to correct in real time for altered beam characteristics introduced by path length changes and thermal lensing of the output coupler. The result is to maintain control of the beam size at the focus optic. In addition, a further integrator produces a signal related to the real time changes in thermal loading of the focal optic as the laser beam is applied and as the input las er power level is adjusted. This correction signal is applied to the focus opti c adjustment mechanism to correct in real time for any shift in the focus opti c caused by thermal lensing of that optic.