Reference-less measurement of the transmission matrix of a highly scattering material using a DMD and phase retrieval techniques

TL;DR

This study presents a method to measure the transmission matrix of a highly scattering medium using a simple optical setup with a DMD and phase retrieval, avoiding the need for a reference beam and enabling efficient characterization.

Contribution

It introduces a reference-less approach combining DMD-based spatial modulation with phase retrieval techniques to estimate the transmission matrix of scattering media.

Findings

Bayesian phase retrieval algorithms outperform other methods in noisy conditions.

The method accurately predicts the transmission matrix and focuses light effectively.

The approach simplifies experimental setup for characterizing scattering media.

Abstract

This paper investigates experimental means of measuring the transmission matrix (TM) of a highly scattering medium, with the simplest optical setup. Spatial light modulation is performed by a digital micromirror device (DMD), allowing high rates and high pixel counts but only binary amplitude modulation. We used intensity measurement only, thus avoiding the need for a reference beam. Therefore, the phase of the TM has to be estimated through signal processing techniques of phase retrieval. Here, we compare four different phase retrieval principles on noisy experimental data. We validate our estimations of the TM on three criteria : quality of prediction, distribution of singular values, and quality of focusing. Results indicate that Bayesian phase retrieval algorithms with variational approaches provide a good tradeoff between the computational complexity and the precision of the estimates.