Real-time full-field imaging through scattering media by all-optical feedback

TL;DR

This paper introduces an ultra-fast all-optical imaging technique using a multimode laser cavity that can image through scattering media in real-time, overcoming limitations of existing methods in speed and scattering effects.

Contribution

The authors develop a novel laser cavity-based imaging method that enables real-time imaging through scattering media by leveraging intra-cavity feedback and phase focusing.

Findings

Imaging through scattering media with diffusion angles below the laser's numerical aperture.

The method can handle temporal variations on timescales as short as 200 ns.

Significantly faster than previous scattering imaging techniques.

Abstract

Full-field imaging through scattering media is fraught with many challenges. Despite many achievements in recent years, current imaging methods are too slow to deal with fast dynamics that occur for example in biomedical imaging. Here we present an ultra-fast all-optical method, where the object to be imaged and the scattering medium (diffuser) are inserted into a highly multimode self-imaging laser cavity. We show that the intra-cavity laser light from the object is mainly focused onto specific regions of the scattering medium where the phase variations are low. Thus, round trip loss within the laser cavity is minimized, thereby overcoming most of the scattering effects. The method is exploited to image objects through scattering media whose diffusion angle is lower than the numerical aperture of the laser cavity. As our method is based on optical feedback inside a laser cavity, it can deal with temporal variations that occur on timescales as short as several cavity round trips, with an upper bound of 200 ns.