Synthetic Light-in-Flight

TL;DR

This paper introduces Synthetic Light-in-Flight (SLiF), a novel computational method that visualizes light paths in volumetric scenes using only continuous wave lasers and standard cameras, overcoming traditional equipment limitations.

Contribution

SLiF is the first approach to generate and manipulate synthetic light-in-flight data using off-the-shelf components, enabling ultrafast light visualization without specialized equipment.

Findings

Successfully visualized volumetric light paths with CW lasers.

Demonstrated manipulation of synthetic light pulses in post-processing.

Characterized scene properties like depth and refractive index using recovered data.

Abstract

Light-in-flight (LiF) measurements enable the visualization of light paths through arbitrary, volumetric scenes, making light-matter interactions at ultrafast timescales visible. Traditionally, LiF measurements require specialized equipment, such as ultrashort pulse light sources and high-speed electronics, often limited by low spatial resolution. Herein, we introduce a novel computational approach,"Synthetic Light-in-Flight" (SLiF), that overcomes these constraints by relying solely on tunable, continuous wave (CW) lasers and off-the-shelf CMOS cameras. From multiple CW scene measurements at different optical wavelengths, we create multiple "synthetic fields," each at a "synthetic wavelength," which is the beat wave of two respective optical waves. These synthetic fields are robust to speckle and environmental fluctuations, enabling us to combine multiple synthetic fields into a "synthetic light pulse" that sections the volumetric scene. Additionally, we demonstrate that these complex synthetic pulse fields can be freely manipulated in the computer after their acquisition, allowing for spatial and temporal shaping of different sets of pulses from the same set of measurements to maximize the decoded information output for each scene. Finally, we show that the recovered time-of-flight information can be used to characterize physical scene properties, such as depth and refractive indices.