  Third harmonic generation (THG) provides a valuable, label-free approach to
imaging biological systems. To date, THG microscopy has been performed using
point scanning methods that rely on intensity measurements lacking phase
information of the complex field. We report the first demonstration of THG
holographic microscopy and the reconstruction of the complex THG signal field
with spatial synthetic aperture imaging. Phase distortions arising from
measurement-to-measurement fluctuations and imaging components cause optical
aberrations in the reconstructed THG field. We have developed an
aberration-correction algorithm that estimates and corrects for these phase
distortions to reconstruct the spatial synthetic aperture THG field without
optical aberrations.
