# Detecting Lateral Motion using Light’s Orbital Angular Momentum

## TL;DR

This paper shows how to detect lateral motion of objects using the orbital angular momentum of light, without needing to reconstruct the object's image.

## Contribution

A novel method for detecting lateral motion using OAM spectral asymmetry in a single tilted light beam.

## Key findings

- Lateral motion can be detected using OAM spectral asymmetry from a single light beam.
- The method works for motion along any axis perpendicular to the light beam and OAM measurement axes.
- The approach extends OAM-based sensing to non-rotational object properties.

## Abstract

Interrogating an object with a light beam and analyzing the scattered light can reveal kinematic information about the object, which is vital for applications ranging from autonomous vehicles to gesture recognition and virtual reality. We show that by analyzing the change in the orbital angular momentum (OAM) of a tilted light beam eclipsed by a moving object, lateral motion of the object can be detected in an arbitrary direction using a single light beam and without object image reconstruction. We observe OAM spectral asymmetry that corresponds to the lateral motion direction along an arbitrary axis perpendicular to the plane containing the light beam and OAM measurement axes. These findings extend OAM-based remote sensing to detection of non-rotational qualities of objects and may also have extensions to other electromagnetic wave regimes, including radio and sound.