Stellar interferometer experiment by measuring visibilities at different wavelengths

In this work we develop an experiment wherein the variation of the fringe visibilities with wavelength provides insights into the geometry of various stellar sources or components. The experiment is based on the Michelson stellar interferometer in which a filter wheel has been inserted between a detecting camera and a telescope obscured by a double aperture lid. The spatial and temporal incoherent light emitting from stellar sources has been simulated using polymer optical fibres and a broadband LED. By measuring the visibilities of the central fringe at different wavelengths we are able to determine the morphology of the analysed light sources, provided that the baseline used is sufficiently long. The experiment is suitable for postgraduate students seeking to delve deeper into light coherence theory and to gain practical experience in optical stellar interferometry.