Transformation of the orbital angular momentum of a beam with optical vortex in an astigmatic optical system

Double sign inversion of the topological charge of an optical vortex was predicted and observed experimentally for a beam focused by a cylindrical lens. Beam evolution after passing through the lens is analyzed by the decomposition of the orbital angular momentum into the «vortical» and «mechanical» components. Topological reactions in the beam wave resulting in the sign inversion of the optical vortex upon the intersection of the wave-front edge dislocation are considered.