  We present differential phase-contrast optical coherence tomography (DPC-OCT)
with two transversally separated probing beams to sense phase gradients in
various directions by employing a rotatable Wollaston prism. In combination
with a two-dimensional mathe- matical reconstruction algorithm based on a
regularized shape from shading (SfS) method accurate quantitative phase maps
can be determined from a set of two orthogonal en-face DPC-OCT images, as
exemplified on various technical samples.
