# Coherent control of light for non-line-of-sight imaging

## TL;DR

This paper introduces a coherent light control method for non-line-of-sight imaging that refocuses laser beams behind obstacles, significantly improving resolution and signal quality for hidden scene detection.

## Contribution

It presents a novel phase control technique combined with speckle memory effect to enhance NLOS imaging resolution and signal-to-noise ratio.

## Key findings

- Achieved spatial resolution below 1 mm.
- Enhanced signal-to-noise ratio with temporally gated detection.
- Demonstrated high-resolution imaging of hidden scenes.

## Abstract

Non-line-of-sight (NLOS) imaging relies on collecting light that is rendered incoherent from the multiple scattering events and is then post-processed to provide an estimate of the hidden scene. Here we employ coherent phase control of the outgoing laser beam phase front so as to refocus the beam behind the obscuring obstacle and then use the speckle memory effect to scan the focused spot across the scene. The back-reflected light intensity provides a direct measurement of the scene with a signal-to-noise ratio that is greatly improved when measured using a temporally gated detector. A spatial resolution of less than 1 mm is demonstrated, opening the way to high-resolution NLOS imaging.