Observation of phase difference in the superposition of two optical vortex beams

A method to measure the phase difference from a superposition of two optical vortex beams is presented. In our recent demonstration, these two vortex beams possess the same topological charge of l = +1 and different topological charges of l = +1 and l = −1. However, they have different initial phases. Our results show differences in the interference patterns at far-field diffraction. We show both theoretical and experimental results, which are in good agreement. Our study can be applied to measure phase objects, where one of the two vortex beams passes through a phase object before the two beams are superimposed.