A conceptual experiment on single-beam coincidence detection with pseudothermal light

Ghost imaging produced by pseudothermal light is commonly obtained by correlating the intensities of two separate beams, neither of which conveys information about the shape of the object to be imaged. The single-beam experiment discussed here, while not exploitable for the practical purpose of reconstructing the shape of a real mask, uses the same mathematical machinery as two-beam experiments; it also suggests that image retrieval by classical light ghost imaging is only a product of normal signal processing and does not involve any "ghost". In addition, the singlebeam setup allows simpler calibration procedures in systematic investigations of the efficiency of coincidence imaging.