  Two-dimensional Talbot array illuminators (TAIs) were designed, fabricated,
and evaluated for high-resolution high-contrast x-ray phase imaging of soft
tissue at 10-20keV. The TAIs create intensity modulations with a high
compression ratio on the micrometer scale at short propagation distances. Their
performance was compared with various other wavefront markers in terms of
period, visibility, flux efficiency and flexibility to be adapted for limited
beam coherence and detector resolution. Differential x-ray phase contrast and
dark-field imaging were demonstrated with a one-dimensional, linear phase
stepping approach yielding two-dimensional phase sensitivity using Unified
Modulated Pattern Analysis (UMPA) for phase retrieval. The method was employed
for x-ray phase computed tomography reaching a resolution of 3$\mu$m on an
unstained murine artery. It opens new possibilities for three-dimensional,
non-destructive, and quantitative imaging of soft matter such as virtual
histology. The phase modulators can also be used for various other x-ray
applications such as dynamic phase imaging, super-resolution structured
illumination microscopy, or wavefront sensing.
