Formation of the spatial structure of pump radiation in the focal plane of a lens for different types of stimulated light scattering

Experiments of our earlier work on the study of stimulated thermal scattering of the second harmonic of neodymium laser radiation in toluene are reproduced in order to confirm the put forward hypothesis about the nature of the laser beam structure decay in the focal plane of a short-focus lens. Experiments were carried out under similar conditions, but with a liquid (CCl4), in which there is no two-photon absorption of the second harmonic radiation from a neodymium laser. A conclusion is made that the spatial structure decay of the laser beam of the second harmonic of the Nd : YAG laser radiation focused by short-focus lenses with a numerical aperture NA ∼ 0.1 in toluene is associated with two-photon absorption.