Detecting photons with orbital angular momentum in extended astronomical objects: application to solar observations

Context. The orbital angular momentum (OAM) of the photon is a property of light from astronomical objects that has not yet been measured. We propose a method of measuring the OAM spectrum of light from an extended natural source, the Sun. Relating the OAM spectrum of different solar areas to its structures could lead to a novel remote sensing technique. Aims. We present a method for measuring the OAM spectrum of solar photons. Methods. The THEMIS