  Blind ptychography is the scanning version of coherent diffractive imaging
which seeks to recover both the object and the probe simultaneously. Based on
alternating minimization by Douglas-Rachford splitting, AMDRS is a blind
ptychographic algorithm informed by the uniqueness theory, the Poisson noise
model and the stability analysis. Enhanced by the initialization method and the
use of a randomly phased mask, AMDRS converges globally and geometrically.
Three boundary conditions are considered in the simulations: periodic,
dark-field and bright-field boundary conditions. The dark-field boundary
condition is suited for isolated objects while the bright-field boundary
condition is for non-isolated objects. The periodic boundary condition is a
mathematically convenient reference point. Depending on the avail- ability of
the boundary prior the dark-field and the bright-field boundary conditions may
or may not be enforced in the reconstruction. Not surprisingly, enforcing the
boundary condition improves the rate of convergence, sometimes in a significant
way. Enforcing the bright-field condition in the reconstruction can also remove
the linear phase ambiguity.
