Atmospheric thermal lens induced by high-power CO2 laser beams in laser materials processing

The atmospheric thermal lens induced by high-power CO2 laser beams in laser materials processing and its influence on beam propagation and focus are s tudied in this paper. It is found in experiments that the atmospheric therm al lens is generated when the air in the beam propagation path is stationar y. But it can be eliminated by blowing air with a certain pressure into the beam's guidance system. Also, the behavior of the beam's propagation under the case of the thermal lens deviates from Gaussian theory. This deviation is calculated by the linear and nonlinear models of the atmospheric therma l lens under the conditions of a large beam diameter and high power intensi ty. In addition, the influence of the thermal lens on the beam's focus size and position is also discussed in this paper.