Wide field fluorescence epi-microscopy behind a scattering medium enabled by speckle correlations

TL;DR

This paper introduces a novel fluorescence microscopy technique that uses speckle correlations and the optical memory effect to image through scattering media, enabling deeper biological imaging.

Contribution

It adapts speckle interferometry principles to fluorescence microscopy, allowing imaging behind turbid layers with robust reconstruction even at low signal levels.

Findings

Successful imaging of micrometer-sized fluorescent objects behind scattering media

Enhanced field of view and resolution compared to traditional methods

Robust phase retrieval algorithm effective in low SNR conditions

Abstract

Fluorescence microscopy is widely used in biological imaging, however scattering from tissues strongly limits its applicability to a shallow depth. In this work we adapt a methodology inspired from stellar speckle interferometry, and exploit the optical memory effect to enable fluorescence microscopy through a turbid layer. We demonstrate efficient reconstruction of micrometer-size fluorescent objects behind a scattering medium in epi-microscopy, and study the specificities of this imaging modality (magnification, field of view, resolution) as compared to traditional microscopy. Using a modified phase retrieval algorithm to reconstruct fluorescent objects from speckle images, we demonstrate robust reconstructions even in relatively low signal to noise conditions. This modality is particularly appropriate for imaging in biological media, which are known to exhibit relatively large optical memory ranges compatible with tens of micrometers size field of views, and large spectral bandwidths compatible with emission fluorescence spectra of tens of nanometers widths.