Measuring orbital angular momentum of vortex beams with double multipoint and ring slit interferometer

Recently, the method of multipoint interferometer (MI) was proposed to detect the orbital angular momentum (OAM), which could be used for measuring OAM of light from astronomical sources. However, this method is limit to low topological charge, because the interference pattern can repeat periodically. In order to solve this problem, we proposed an improved multipoint interferometer method (IMI) capable of measuring the OAM of optical vortex with arbitrary topological charge. However, the method of IMI is limited by complex interference patterns detection difficult. To overcome these disadvantages of MI and IMI, we proposed a method called DRI using screen plate with a binary ring slit and two pinholes. This method is demonstrated viability theoretically