Using a multipoint interferometer to measure the orbital angular momentum of light in astrophysics

Recently it was shown that the orbital angular momentum of light can be measured using a multipoint interferometer, a system in which the light from several point measurements is interferometrically combined. This system has important applications in optics but could also be employed to detect astrophysical orbital angular momentum. Until now, the response of a multipoint interferometer to an on-axis, normally incident Laguerre-Gaussian beam has been studied by visual inspection. In this paper we present an algorithm to determine the orbital angular momentum of the impinging beam from the obtained interference patterns. Using this algorithm we extend our study to general optical vortices and a superposition of optical vortices.