Thermal blooming of laser beams in fluids.

Thermal blooming of laser beams in liquids and gases has been studied using geometrical optics. The intensity profiles, light rays, and fluid density changes are determined as functions of time and of the initial beam profile. Short and long time behavior are derived. The effects of thermal conduction and viscosity. are included. Special beam profiles such as a uniformly illuminated aperture, a parabolic profile, and a Gaussian beam are treated. The on-axis beam intensity as given by the theory is compared to the data proved by Kenemuth et al. and is shown to fit within the experimental error.