  Holographic microscopy combined with forward modeling and inference allows
colloidal particles to be characterized and tracked in three dimensions with
high precision. However, current models ignore the effects of optical
aberrations on hologram formation. We investigate the effects of spherical
aberration on the structure of single-particle holograms and on the accuracy of
particle characterization. We find that in a typical experimental setup,
spherical aberration can result in systematic shifts of about 2% in the
inferred refractive index and radius. We show that fitting with a model that
accounts for spherical aberration decreases this aberration-dependent error by
a factor of two or more, even when the level of spherical aberration in the
optical train is unknown. With the new generative model, the inferred
parameters are consistent across different levels of aberration, making
particle characterization more robust.
