Conventional incoherent imaging based on measuring the spatial intensity
distribution in the image plane faces the resolution hurdle described by the
Rayleigh diffraction criterion. Here, we demonstrate theoretically using the
concept of the Fisher information that quadrature statistics measured by means
of array homodyne detection enables estimation of the distance between two
incoherent point sources well below the Rayleigh limit for sufficiently high
signal-to-noise ratio. This capability is attributed to the availability of
spatial coherence information between individual detector pixels acquired using
the coherent detection technique. A simple analytical approximation for the
precision attainable in the sub-Rayleigh region is presented. Furthermore, an
estimation algorithm is proposed and applied to Monte Carlo simulated data.Comment: 10 pages, 6 figures, accepted for publication in Phys. Rev.
