Intensity-corrected 4D light-in-flight imaging

TL;DR

This paper introduces a model that corrects for relativistic, scattering, and optical effects in 4D light-in-flight imaging, enabling accurate reconstruction of a laser pulse’s true path in space and time.

Contribution

The authors develop a comprehensive correction model for light-in-flight imaging that accounts for multiple physical effects, improving the accuracy of optical path reconstruction.

Findings

Successfully reconstructs the true intensity-corrected light path in 4D.

Validates the model with SPAD array data of laser propagation.

Demonstrates correction of intensity variations along the light path.

Abstract

Light-in-flight (LIF) imaging is the measurement and reconstruction of light's path as it moves and interacts with objects. It is well known that relativistic effects can result in apparent velocities that differ significantly from the speed of light. However, less well known is that Rayleigh scattering and the effects of imaging optics can lead to observed intensities changing by several orders of magnitude along light's path. We develop a model that enables us to correct for all of these effects, thus we can accurately invert the observed data and reconstruct the true intensity-corrected optical path of a laser pulse as it travels in air. We demonstrate the validity of our model by observing the photon arrival time and intensity distribution obtained from single-photon avalanche detector (SPAD) array data for a laser pulse propagating towards and away from the camera. We can then reconstruct the true intensity-corrected path of the light in four dimensions (three spatial dimensions and time).