Enhanced nonlinear imaging through scattering media using transmission matrix based wavefront shaping

TL;DR

This paper demonstrates that transmission matrix-based wavefront shaping significantly enhances nonlinear imaging depth and quality in scattering media, enabling practical deep tissue imaging with ultrashort pulses.

Contribution

It introduces broadband transmission matrix techniques for nonlinear imaging, achieving substantial signal enhancement and compatibility with fast scanning methods in scattering media.

Findings

Nonlinear signal enhancement of several orders of magnitude.

Effective imaging through millimeters of scattering tissue.

Compatibility with fast nonlinear scanning and acoustic methods.

Abstract

Despite the tremendous progresses in wavefront control through or inside complex scattering media, several limitations prevent reaching practical feasibility for nonlinear imaging in biological tissues. While the optimization of nonlinear signals might suffer from low signal to noise conditions and from possible artifacts at large penetration depths, it has nevertheless been largely used in the multiple scattering regime since it provides a guide star mechanism as well as an intrinsic compensation for spatiotemporal distortions. Here, we demonstrate the benefit of Transmission Matrix (TM) based approaches under broadband illumination conditions, to perform nonlinear imaging. Using ultrashort pulse illumination with spectral bandwidth comparable but still lower than the spectral width of the scattering medium, we show strong nonlinear enhancements of several orders of magnitude, through thicknesses of a few transport mean free paths, which corresponds to millimeters in biological tissues. Linear TM refocusing is moreover compatible with fast scanning nonlinear imaging and potentially with acoustic based methods, which paves the way for nonlinear microscopy deep inside scattering media.