Non-invasive dynamic or wide-field imaging through opaque layers and around corners

TL;DR

This paper introduces a novel optical imaging method that uses phase information of the transfer function to achieve non-invasive, high-speed, wide-field imaging through opaque layers and around corners, even under weak illumination.

Contribution

It presents a new approach that characterizes wave distortions using only phase of the optical transfer function, enabling rapid, reliable imaging of dynamic objects behind turbid media.

Findings

Achieved noninvasive video imaging at 25-200 Hz of moving objects in turbid media.

Enabled imaging under weak illumination conditions.

Demonstrated imaging of a hidden photoluminescent sample through multiple opaque layers.

Abstract

In turbid media, scattering of light scrambles information of the incident beam and represents an obstacle to optical imaging. Noninvasive imaging through opaque layers is challenging for dynamic and wide-field objects due to unreliable image reconstruction processes. We here propose a new perspective to solve these problems: rather than using the full point-spread-function (PSF), the wave distortions in scattering layers can be characterized with only the phase of the optical-transfer-function (OTF, the Fourier transform of PSF), with which diffraction-limit images can be analytically solved. We then develop a method that exploits the redundant information dynamic objects, and can reliably and rapidly recover OTFs' phases within several iterations. It enables not only noninvasive video imaging at 25 ~ 200 Hz of a moving object hidden inside turbid media, but also imaging under weak illumination that is inaccessible with previous methods. Furthermore, by scanning a localized illumination on the object plane, we propose a wide-field imaging approach, with which we demonstrate an application where a photoluminescent sample hidden behind four-layers of opaque polythene films is imaged with a modified multi-photon excitation microscopy setup.