The effect of a thermal lens at double-beam laser action on a magnetic fluid

A light-induced inhomogeneity in the form of a lens of thermal nature in a magnetic fluid, which is a colloidal solution of magnetite, has been studied using two laser beams. The application of this scheme made it possible to independently observe the occurrence of a feature in the area of an intense laser beam by registering a diffraction pattern in an additional weak probing beam. It was found that the size of the diffraction patterns formed in each of these rays depends on the magnetic field.