Superluminal Motion-Assisted 4-Dimensional Light-in-Flight Imaging

TL;DR

This paper presents the first 4D light-in-flight imaging capturing superluminal motion using a novel time-gated single-photon camera and machine learning, enabling detailed visualization of ultrafast light propagation.

Contribution

The work introduces a new 4D imaging method combining superluminal motion observation, high-resolution video, and machine learning analysis without prior knowledge or complex scanning.

Findings

Successful 4D light-in-flight imaging with superluminal motion detection

High-resolution videos generated without laser scanning or interpolation

Reconstruction accuracy aligns well with actual light path geometry

Abstract

Advances in high speed imaging techniques have opened new possibilities for capturing ultrafast phenomena such as light propagation in air or through media. Capturing light-in-flight in 3-dimensional xyt-space has been reported based on various types of imaging systems, whereas reconstruction of light-in-flight information in the fourth dimension z has been a challenge. We demonstrate the first 4-dimensional light-in-flight imaging based on the observation of a superluminal motion captured by a new time-gated megapixel single-photon avalanche diode camera. A high resolution light-in-flight video is generated with no laser scanning, camera translation, interpolation, nor dark noise subtraction. A machine learning technique is applied to analyze the measured spatio-temporal data set. A theoretical formula is introduced to perform least-square regression, and extra-dimensional information is recovered without prior knowledge. The algorithm relies on the mathematical formulation equivalent to the superluminal motion in astrophysics, which is scaled by a factor of a quadrillionth. The reconstructed light-in-flight trajectory shows a good agreement with the actual geometry of the light path. Our approach could potentially provide novel functionalities to high speed imaging applications such as non-line-of-sight imaging and time-resolved optical tomography.