Distinguishing orbital angular momenta and topological charge in optical\n vortex beams

In this work we discuss how the classical orbital angular momentum (OAM) and\ntopological charge (TC) of optical beams with arbitrary spatial phase profiles\nare related to the local winding density. An analysis for optical vortices (OV)\nwith non-cylindrical symmetry is presented and it is experimentally shown for\nthe first time that OAM and TC may have different values. The new approach also\nprovides a systematic way to determine the uncertainties in measurements of TC\nand OAM of arbitrary OV.\n