Material processing using polarisation-modulated laser beam - altering phase difference between two orthogonal vector components of polarisation as function of time

摘要

The Co2 laser (10) has a commencing power sufficient for material processing, and delivers a linearly polarised laser beam (12). The laser beam passes through a phase modulator (14) and then drops via a deflecting mirror (16) into a laser head (18) forming part of a robot. The laser head contains two deflecting mirrors (20) and a focussing lens (24). One deflecting mirror (20) is rotatable around an axis (26), and the other is rotatable with the focussing lens (24) around a further axis (28) in order to achieve a desired orientation of the focussed laser beam. In practice, normally several rotatable located deflecting mirrors and several degrees of movement freedom are provided. The focussed laser beam drops on to the upper surface of a workpiece (30) arranged on a support (32) with which it is movable in a specific direction (34) in relation to the focussed laser beam. A modulator (14) is also provided for the polarisation condition of the laser beam. ADVANTAGE - For material processing by laser beam, the polarisation of which is modulated.