Abstract

The source image spectrum obtained by imaging interferometry is derived from measurements of the interference fringe visibility and phase from pairs of apertures. Most interesting sources are dim and of small angular extent requiring observations in the low light level regime over large baselines. The use of large individual apertures increases the amount of light but requires some form of adaptive optics to mitigate the effects of the atmosphere and maintain the spatial coherence across baselines. We outline the mathematical formalism for quantifying the error in estimating the fringe visibility and phase with varying amounts of spectral bandwidth, radiometric signal-to-noise, atmospheric seeing, individual aperture diameter, baseline dimension, fringe tracking, tilt removal, and higher order Zernike mode removal. This work describes the proper aperture wavefront covariances across arbitrary baselines with the proper Kolmogorov atmospheric statistics, assumed independent by other works. Photon noise, detector noise, and spectral bandwidth dependent photon counting statistics are included. The effects from the use of single mode fiber optics to transport the beams are also described. Numerical results describing the sensitivity of the fringe estimates to the above parameters are presented for typical array geometries for observing geosyncronous satellites.

© 1995 Optical Society of America