  The estimation of phase errors from digital-holography data is critical for
applications such as imaging or wave-front sensing. Conventional techniques
require multiple i.i.d. data and perform poorly in the presence of high noise
or large phase errors. In this paper we propose a method to estimate
isoplanatic phase errors from a single data realization. We develop a
model-based iterative reconstruction algorithm which computes the maximum a
posteriori estimate of the phase and the speckle-free object reflectance. Using
simulated data, we show that the algorithm is robust against high noise and
strong phase errors.
