The Rise of the Brown–Twiss Effect

Despite the simplicity of flux collecting hardware, robustness to misalignments, and immunity to seeing conditions, Intensity Correlation Imaging arrays using the Brown–Twiss effect to determine two-dimensional images have been burdened with very long integration times. The root cause is that the essential phase retrieval algorithms must use image domain constraints, and the traditional signal-to-noise calculations do not account for these. Thus, the conventional formulations are not efficient estimators. Recently, the long integration times have been emphatically removed by a sequence of papers. This paper is a review of the previous theoretical work that removes the long integration times, making the Intensity Correlation Imaging a practical and inexpensive method for high-resolution astronomy.