  We describe a simple and robust approach for characterizing the shift-variant
pupil aberrations of wide field-of-view microscopy systems. We derive the
location-dependent pupil transfer functions by first capturing multiple
intensity images at different defocus settings; a generalized pattern search
(GPS) algorithm is then applied to recover the complex pupil functions at ~350
different spatial locations over the entire field-of-view. Parameter fitting
transforms these pupil functions into accurate 2D aberration maps. We
demonstrate shift-variant aberration compensation by using an
information-preserving image deconvolution scheme over the entire
field-of-view. Such automated shift-variant pupil characterization will
facilitate new approaches of aberration correction for future gigapixel imaging
platforms.
