Tracking and imaging of dynamic objects in scattering media by time-reversed adapted-perturbation (TRAP) optical focusing

TL;DR

This paper introduces a non-invasive method to focus and image light inside scattering media by using intrinsic dynamic changes as guide stars, enabling applications like tracking and imaging in complex environments.

Contribution

It presents a novel adaptive time-reversal technique that uses spontaneous permittivity changes as intrinsic guide stars for optical focusing and imaging.

Findings

Successfully focused light on moving targets within scattering media

Enabled imaging of time-variant objects without physical contact

Demonstrated potential for real-world applications like fog and tumor imaging

Abstract

The ability to steer light propagation inside scattering media has long been sought-after due to its potential widespread applications. To form optical foci inside scattering media, the only feasible strategy is to guide photons by using either implanted or virtual guide stars. However, all of these guide stars must be introduced extrinsically, either invasively or by physical contact, limiting the scope of their application. Here, we focus light inside scattering media by employing intrinsic dynamics as guide stars. By time-reversing the perturbed component of the scattered light adaptively, we concentrate light to the origin of the perturbation, where the permittivity varied spontaneously. We demonstrate dynamic light focusing onto moving targets and imaging of a time-variant object obscured by highly scattering media, without invasiveness and physical contact. Anticipated applications include all-weather optical communication with airplanes or satellites, tracking vehicles in thick fogs, and imaging and photoablation of angiogenic vessels in tumors.