Passive interferometric 3-D imaging and incoherence gating

This paper proposes interferometric 3-D imaging based on retrieving the space variant cross-spectral density. The cross-spectral density across an arbitrary transverse plane can be retrieved by using the propagation law described in the Fourier domain. The 3-D intensity distribution is reconstructed from a series of the cross-spectral densities across planes within the slab geometry considered. Results of an experiment conducted by incorporating two point sources are also reported. The point spread function of the proposed interferometric imaging system, and its similarity to an ordinary imaging system are discussed. To detect spatially incoherent sources, we also propose an incoherence gating method based on the present interferometric imaging technique. The second-order differential of the series of retrieved cross-spectral densities with respect to a two-point separation enable us to estimate field correlations over the 3-D field, and locations of primary sources are clearly determined. (C) 1999 Elsevier Science B.V. All rights reserved.