Improved characterization of colloidal spheres by modeling effects of spherical aberration in digital holography microscopy

With digital holographic microscopy (DHM), individual colloidal particles can be characterized and tracked in three dimensions and at high frame rates. Recent advances in forward modeling and inference now allow the size, shape, and position of individual particles to be determined much more precisely than in previous approaches based on reconstruction of the hologram. However, current forward models of hologram formation ignore the effects of aberrations in the optical train. We show that spherical aberration at typical levels leads to systematic errors in the inferred parameters that depend on the level of aberration. We develop a model for spherical aberration and fit it to experimental data. We show that this approach reduces the systematic error due to aberration and allows us to recover parameters that are consistent at differing levels of aberration.