Phase control algorithms for focusing light through turbid media

TL;DR

This paper introduces three algorithms for dynamically controlling wavefronts to focus light through scattering media, with analysis of their performance and noise sensitivity, enabling improved light delivery in biological tissues.

Contribution

The paper presents new algorithms for real-time wavefront shaping in scattering media, analyzing their dynamic behavior and noise robustness through experiments and simulations.

Findings

Algorithms successfully focus light through turbid media

Performance varies with measurement noise levels

Model accurately predicts algorithm behavior

Abstract

Light propagation in materials with microscopic inhomogeneities is affected by scattering. In scattering materials, such as powders, disordered metamaterials or biological tissue, multiple scattering on sub-wavelength particles makes light diffuse. Recently, we showed that it is possible to construct a wavefront that focuses through a solid, strongly scattering object. The focusing wavefront uniquely matches a certain configuration of the particles in the medium. To focus light through a turbid liquid or living tissue, it is necessary to dynamically adjust the wavefront as the particles in the medium move. Here we present three algorithms for constructing a wavefront that focuses through a scattering medium. We analyze the dynamic behavior of these algorithms and compare their sensitivity to measurement noise. The algorithms are compared both experimentally and using numerical simulations. The results are in good agreement with an intuitive model, which may be used to develop dynamic diffusion compensators with applications in, for example, light delivery in human tissue.