Study of thermal effects on wavefront distribution in a high-power laser processing head

Abstract

The intricate thermal phenomena including thermotropic deformation and thermal blooming effect inside the cavity of a twelve-kilowatt power laser processing head were thoroughly investigated using COMSOL Multiphysics software. By constructing the mapping relationship between the wavefront aberration/focal plane position maps of collimating and focusing lenses and the thermal effects, the influence laws on lens body/coating deformations and thermally induced deformations of the clamping mechanism for the lens surface temperature were achieved and visualized, as well as how these deformations further altered the beam quality and wavefront. Meanwhile, the experimental verification based on the Shack-Hartmann wavefront sensor ensured the accuracy of the simulation results. In addition, it was also explored that controlling the gas flow rate in the cavity in the range of 0.13 m/s-0.15 m/s under a helium environment can effectively alleviate the focal plane shift caused by the thermal blooming effect. These findings are of practical significance for optimizing the processing quality of high-power laser, especially in controlling thermal effect.