Special features of laser diagnostics of gas flows in a thick-walled glass pipe

The article presents application of optical gradient methods for the research of inhomogeneity of gas flows through a thick-walled glass cylinder. The influence of not only inhomogeneous gas medium, but also cylinder walls on the process of laser radiation propagation was researched. Methods for describing the refraction of the laser sheet for various cases of its orientation in space in geometrical optics approximation were worked out. The analysis of displacement of the laser sheet's sections on the screen after penetration through inhomogeneity was conducted. Calculations of the laser sheet's shape distortion during penetration through a transparent hollow cylinder were performed. Theoretical distributions of the laser sheet's sections on the screen were constructed. Various cases of the laser sheet orientation in space were considered. The influence of an optically inhomogeneous medium on the laser sheet's shape were considered. (paper)