Measuring large optical reflection matrices of turbid media

TL;DR

This paper demonstrates the measurement of a large optical reflection matrix of a highly disordered medium, revealing correlations and potential for enhanced energy delivery, with implications for light therapy.

Contribution

It introduces a method to measure large reflection matrices of turbid media and analyzes their eigenvalue distributions considering optical limitations.

Findings

Measured a large optical reflection matrix exceeding the number of resolvable modes.

Observed correlations in the reflection matrix consistent with random-matrix theory.

Indicated potential for improved light delivery in scattering media.

Abstract

We report the measurement of a large optical reflection matrix (RM) of a highly disordered medium. Incident optical fields onto a turbid sample are controlled by a spatial light modulator, and the corresponding fields reflected from the sample are measured using full-field Michelson interferometry. The number of modes in the measured RM is set to exceed the number of resolvable modes in the scattering media. We successfully study the subtle intrinsic correlations in the RM which agrees with the theoretical prediction by random-matrix theory when the effect of the limited numerical aperture on the eigenvalue distribution of the RM is taken into account. The possibility of the enhanced delivery of incident energy into scattering media is also examined from the eigenvalue distribution which promises efficient light therapeutic applications.