  As a special experimental technique, weak measurement extracts very little
information about the measured system and will not cause the measured state
collapse. When coupling the orbital angular momentum (OAM) state with a
well-defined pre-selected and post-selected system of a weak measurement
process, there is an indirect coupling between position and topological charge
(TC) of OAM state. Based on these ideas, we propose an experimental scheme that
experimentally measure the TC of OAM beams from -14 to 14 through weak
measurement.
