Large depth-of-field tracking of colloidal spheres in holographic microscopy by modeling the objective lens

TL;DR

This paper enhances 3D holographic particle tracking by modeling the objective lens, significantly increasing the depth of field and enabling accurate tracking of particles across various focal planes.

Contribution

It introduces a lens effect model into holographic microscopy, allowing for more accurate 3D particle tracking across a broader depth range.

Findings

Doubling the depth of field in holographic microscopy.

Modeling the lens effect reduces systematic errors in particle position.

Conditions identified where ignoring lens effects causes significant inaccuracies.

Abstract

Holographic microscopy has developed into a powerful tool for 3D particle tracking, yielding nanometer-scale precision at high frame rates. However, current particle tracking algorithms ignore the effect of the microscope objective on the formation of the recorded hologram. As a result, particle tracking in holographic microscopy is currently limited to particles well above the microscope focus. Here, we show that modeling the effect of an aberration-free lens allows tracking of particles above, near, and below the focal plane in holographic microscopy, doubling the depth of field. Finally, we use our model to determine the conditions under which ignoring the effect of the lens is justified, and in what conditions it leads to systematic errors.