Refraction of an astigmatic laser beam in a transition layer of a stratified liquid

Refraction of an astigmatic laser beam in a transition layer formed at the boundary between two liquids with different optical characteristics is studied theoretically and experimentally. An algorithm of calculating a ray trajectory in the transition layer of a stratified liquid is considered. The profile of the refractive index in the medium is modeled for three different distributions: linear, sinusoidal, and tangential. Computer modeling based on the above models allowed obtaining two- and three-dimensional images of the laser beam (refractograms) inside and outside of the medium. The influence of the beam parameters and the experimental layout on the shape of refractograms is studied, and optimal experimental conditions are determined. The experimental arrangement for detection of 2D and 3D refractograms by the laser refractography method is described. An experimental technique is developed, and digital registration of the experimental refractograms is carried out. Adaptation of special software for processing 2D refractograms allowed retrieving the refractive index profile in the transition layer of a liquid. Based on the tangential model of the diffusion layer in a saltstratified liquid, the values of the refractive index were obtained that allowed determining the salinity profile in the given layer.