Topological charge of a vortex beam using Hadamard matrix pattern of circular apertures

Abstract

We propose a method to determine the topological charge (TC) of a vortex beam using a computer generated Hadamard matrix pattern of square planar array of circular apertures using MATLAB. When the generated apertures are illuminated by optical vortex beams, the far-field diffraction patterns can be utilized to determine the TC of the vortex beams. We found that the magnitude and sign of the TC can be inferred from the intensity centroid value of the diffraction patterns. This method provides a simpler approach in measuring TC as it relies on the intensity and not on the structure of the diffraction pattern itself.