Measuring the orbital angular momentum of optical vortices using a multipinhole plate

We present a method for measuring the orbital angular momentum (OAM) of optical vortices through extracting the phase values sampled by a multipinhole plate. We demonstrate that the phase of an optical vortex passing through a multipinhole plate can be directly extracted from the Fourier transform of a single diffraction intensity pattern according to a simple algorithm and thus the l state or the OAM of the photons can be measured quantitatively.