  Focal plane arrays of bolometers are increasingly employed in astronomy at
far--infrared to millimetre wavelengths. The focal plane fields and the
detectors are both partially coherent in these systems, but no account has
previously been taken of the effect of partial coherence on array performance.
In this paper, we use our recently developed coupled--mode theory of detection
together with Fisher information matrix techniques from signal processing to
characterize the behaviour of partially coherent imaging arrays. We investigate
the effects of the size and coherence length of both the source and the
detectors, and the packing density of the array, on the amount of information
that can be extracted from observations with such arrays.
