Refractometry of optically inhomogeneous media based on recording the position of caustics using structured laser radiation

This paper deals with the refractometry of optically inhomogeneous media under conditions of significant refraction of probing beams due to substantial gradients of the refractive index and the length of the test medium. For these conditions, wave and beam refraction models of laser beams in the presence of caustics are developed. The advantages of using structured beams to record caustics for the purpose of quantitative diagnostics of inhomogeneities of the refractive index are discussed. Based on the developed models, possible methods are proposed to solve the inverse refraction problem and reconstruct the refractive index values in inhomogeneity cross-sections.