Alignment Sensitivity of Stable Resonators Measured at a Fast Axial Flow CO2 High Power Laser

Reproducible laser materials processing with high power CO₂ lasers requires among others high long-time stability of the laser output power. Mechanical stability of the resonator structure has great influence on the temporal behaviour of laser output power because small mechanical deformation uf the resonator structure leads to misalignment of the resonator and therefore to a decrease of output power. Temporal deformations of the resonator structure by mechanical or thermal stresses lead to temporal fluctuations of the laser output power with a time scale of minutes. The alignment sensitivity of a resonator configuration gives requirements for the mechanical stability of the resonator structure. We have measured the output power drop by misalignment of the resonator for several resonator configurations of a linear stable long-radius resonator. The results are presented in this paper in comparison with a simple theoretical model of the alignment sensitivity for 10% power drop.