Spin–Orbital Transformation in a Tight Focus of an Optical Vortex with Circular Polarization

In the framework of Richards–Wolf formalism, spin–orbit conversion upon tight focusing an optical vortex with circular polarization is studied. We obtain exact formulas which show what part total (averaged over beam cross-section) longitudinal spin angular momentum transferred to orbital in focus. It shown that maximum can be transformed into equal half power, and this reached at numerical aperture one. prove transforms does not depend on topological charge. also by virtue spin–orbital focusing, energy flux decreases partially whole transversal (azimuthal) flow Moreover, exactly same amount decreases.