Intensity interferometry measures the square of the absolute value of the normalized coherence function. The phase of the coherence function is lost. The possibility of deriving the phase function by using higher-order intensity correlations from the signal collected by a large array of mirrors is discussed. The array is not phased and each mirror is considered to be of the intensity interferometer type, i.e., it only concentrates light onto a detector without regard to the imaging quality. Knowledge of the coherence function yields the two-dimensional intensity distribution of self-luminous or intrinsically luminous objects.
A. S. Marathay, A. S. Marathay,
"Phase Function Of Spatial Coherence From Multiple Intensity Correlations", Proc. SPIE 0628, Advanced Technology Optical Telescopes III, (20 August 1986); doi: 10.1117/12.963540; https://doi.org/10.1117/12.963540