We study the imaging sensitivity of a ground-based optical array of n apertures in which the beams are combined pairwise, as in radio-interferometric arrays, onto n(n − 1)/2 detectors, the so-called nC2 interferometer. Ground-based operation forces the use of the fringe power and the bispectrum phasor as the primary observables rather than the simpler and superior observable, the Michelson fringe phasor. At high photon rates we find that bispectral imaging suffers no loss of sensitivity compared with an ideal array (space based) that directly uses the Michelson fringe phasor. In the opposite limit, when the number of photons per spatial coherence area per coherence time drops below unity, the sensitivity of the array drops rapidly relative to an ideal array. In this regime the sensitivity is independent of n, and hence it may be efficient to have many smaller arrays, each operating separately and simultaneously.
© 1991 Optical Society of America
Original Manuscript: April 9, 1990
Manuscript Accepted: September 17, 1990
Published: March 1, 1991
Shrinivas R. Kulkarni, Sudhakar Prasad, and Tadashi Nakajima, "Noise in optical synthesis images. II. Sensitivity of an nC2 interferometer with bispectrum imaging," J. Opt. Soc. Am. A 8, 499-510 (1991)