Focus plane estimation in digital holographic microscopy

We present a new method to achieve digital autofocus in holography. This method relies on the insertion of calibrated beads into the studied sample. Reconstructing the position and the radius of the beads using Inverse Problems Approach, based on Mie Model, makes it possible to accurately locate the slide on which the sampled is placed. Numerical focusing can then be performed using the standard backpropagation method or regularized reconstruction. Because the reconstruction plane can be chosen objectively with respect to the position of the slide, this numerical autofocus is reproducible whatever is the type of the observed biological sample.