Phase correction of radiation emitted by a powerful industrial laser with higher mode selection

Special features of operation of a high-power industrial CO₂ laser with selection and correction of the phases of higher transverse modes are investigated theoretically and experimentally. An effective conversion of the higher-mode oscillation field into a narrow beam with inphase optical oscillations with an output power up to 1 kW with the help of a phase corrector is reported for the first time. The angular divergence is reduced to one-third of the value typical of a multimode beam. The physical origin of intracavity aberrations, which deteriorate the beam quality, is analysed. It is shown that the most significant effect is produced by an optical wedge-type aberration emerging due to transverse circulation of the active medium and transverse discharge. The prospects of application of this method for obtaining more powerful narrow laser beams are discussed.