Automatic alignment of a high-power CO2 laser resonator

An on-line, electronic feedback approach for automatic alignment of a laser resonator is described. A measure of the resonator alignment error is derived by partitioning a 1% sample of the laser output into quadrants, and using standard electronic circuits to compare the average power present in each quadrant. A motorized X — Y alignment system is then used to implement the alignment changes required to maintain optimum output quality from the laser. The system is shown capable of stabilizing the output power in each quadrant of the beam to within about 2% of the optimum level.