Toward spectral intensity interferometry

We use intensity interferometry to image a group of point sources in a computer simulation and laboratory demonstration. We acquire the image of this "asterism" by measuring the second- and third-order correlations between photon arrival times using three single photon detectors. To reduce noise effects, we divide the light collector into segments, and each segment is dispersed into spectral bands, where photons in each band are correlated separately. This comprises a new optical design that (1) is stable for partially collimated beams, (2) is light efficient, and (3) is not any wider than the incoming beam.