  Digital aberration measurement and removal play a prominent role in
computational imaging platforms aimed at achieving simple and compact optical
arrangements. A recent important class of such platforms is Fourier
ptychography, which is geared towards efficiently creating gigapixel images
with high resolution and large field of view (FOV). In current FP
implementations, pupil aberration is often recovered at each small segment of
the entire FOV. This reconstruction strategy fails to consider the
field-dependent nature of the optical pupil. Given the power series expansion
of the wavefront aberration, the spatially varying pupil can be fully
characterized by tens of coefficients over the entire FOV. With this
observation, we report a Full-field Fourier Ptychography (FFP) scheme for rapid
and robust aberration metrology. The meaning of 'full-field' in FFP is referred
to the recovering of the 'full-field' coefficients that govern the
field-dependent pupil over the entire FOV. The optimization degrees of freedom
are at least two orders of magnitude lower than the previous implementations.
We show that the image acquisition process of FFP can be completed in ~1s and
the spatially varying aberration of the entire FOV can be recovered in ~35s
using a CPU. The reported approach may facilitate the further development of
Fourier ptychography. Since no moving part or calibration target is needed in
this approach, it may find important applications in aberration metrology. The
derivation of the full-field coefficients and its extension for Zernike modes
also provide a general tool for analyzing spatially varying aberrations in
computational imaging systems.
