Active optics for the focus control of material processing CO2-laser machines

摘要

Abstract: aterial processing is becoming more and more important for high precision applications. This precision is often not keepable in laser machines with 'flying optics' because of the varying distance between laserresonator and focussing optics, the distance between focussing optics and 'TCP' (focal point) varies too; and because of moving mirrors along the beam propagation path, the angle between beam axis and machine axis is fluctuating during the process. These effects have an impact on the result of the process and diminue the effectiveness and precision of laser material processing. We have developed and tested a system, consisting of an active mirror and a sensor that is positional directly in the 'flying optics' before the focussing optic. The active mirror can be tilted in both directions perpendicular to the beam axis and is spherically deformable. The sensor couples out a minute of the laser beam by a hole grating and measures the important beam parameters. A control unit drives the adaptive mirror with regard to the sensor signals. The system makes the 3- D on-line control of the focal point possible.!0