Non-invasive focusing and imaging in scattering media with a fluorescence-based transmission matrix

Antoine Boniface,Jonathan Dong,Sylvain Gigan

doi:10.1038/s41467-020-19696-8

Abstract

In biological microscopy, light scattering represents the main limitation to image at depth. Recently, a set of wavefront shaping techniques has been developed in order to manipulate coherent light in strongly disordered materials. The Transmission Matrix approach has shown its capability to inverse the effect of scattering and efficiently focus light. In practice, the matrix is usually measured using an invasive detector or low-resolution acoustic guide stars. Here, we introduce a non-invasive and all-optical strategy based on linear fluorescence to reconstruct the transmission matrices, to and from a fluorescent object placed inside a scattering medium. It consists in demixing the incoherent patterns emitted by the object using low-rank factorizations and phase retrieval algorithms. We experimentally demonstrate the efficiency of this method through robust and selective focusing. Additionally, from the same measurements, it is possible to exploit memory effect correlations to image and reconstruct extended objects. This approach opens up a new route towards imaging in scattering media with linear or non-linear contrast mechanisms.

Highlights

In biological microscopy, light scattering represents the main limitation to image at depth
Optics has been combined with acoustics to coarsely locate each target[11,12], which enables the reconstruction of a transmission matrix (TM) but requires complicated acousto-optical setups
Imaging fluorescent objects through thin scattering media can be done thanks to the memory effect[17,18], a general method to focus on fluorescent objects at depth, and image them if they extend beyond the memory effect is still missing

Summary

Introduction

Light scattering represents the main limitation to image at depth. Even if each target has its own optical response, what is measured in epi-detection is the back-scattered emission, spatially and temporally mixed To overcome this limitation, optics has been combined with acoustics to coarsely locate each target[11,12], which enables the reconstruction of a TM but requires complicated acousto-optical setups. Optics has been combined with acoustics to coarsely locate each target[11,12], which enables the reconstruction of a TM but requires complicated acousto-optical setups Another powerful approach relies on the measurement of a time-gated matrix in reflection[13,14], but is based on retroreflected ballistic photons, limited in depth. If the medium exhibits limited memory effect, we show that an image of the object can be retrieved, even when its size exceeds the memory effect range

Methods

Results

Conclusion