Thermally Induced Modifications of a High Power cw Laser Beam

The problem of beam-induced thermal modifications of a high powered cw laser beam is considered. The extent and type of modification depend principally upon the nature of the medium (liquid or air) and whether an external flow field is present. These conditions determine the dominant heat loss mechanism operating the fluid: forced convection, free convection, and diffusion and, thus, the beam distortions. All three cases are analyzed and figures presented, showing the type of distortion expected as determined within the framework of geometric optics.