Determination of the radiation axis position of an unstable-cavity laser

Propagation of an alignment laser beam through an unstable cavity laser is numerically simulated. It is shown that the axis of the expanded beam coincides with that of the fundamental laser radiation within an accuracy of no less than 1'' even under cavity misalignment of up to 30''. Experiments on determining the position of the radiation axis of a high-power pulsed unstable cavity chemical laser and various cavity misalignments confirm the calculation results.