Abstract: The self - interference phenomenon of a vortex beam passing through a single splitting prism is

analyzed theoretically and studied experimentally. The results show that the self-interference fringes of the vortex

beams are twisted，which are different from the interference of a vortex beam with a plane or spherical wave. At the

edge of the interference fringes，the number of fracture stripes will increase with the increase of the vortex

　　topological charge，and the direction of the fracture stripe is determined by the symbol of topological charge. The

　　above conclusion provides a new method for measuring the topological charges of vortex beams in a simple way.

Key words: vortex beam, splitting prism, interferometry, topological charge