Using ultra-short pulses to determine particle size and density distributions

TL;DR

This paper presents a method to analyze the particle size distribution and packing density in strongly scattering media using the time-dependent response of ultra-short light pulses, enabling independent assessment of these properties.

Contribution

It introduces a novel approach to determine particle size and packing fraction from pulse spreading and proposes a new technique to measure the shape of ultra-short pulses after propagation.

Findings

Pulse spreading depends on particle size, distribution, and packing density.

Intensity over time can independently reveal particle size distribution and packing fraction.

New method for measuring ultra-short pulse shape after scattering.

Abstract

We analyze the time dependent response of strongly scattering media (SSM) to ultra-short pulses of light. A random walk technique is used to model the optical scattering of ultra-short pulses of light propagating through media with random shapes and various packing densities. The pulse spreading was found to be strongly dependent on the average particle size, particle size distribution, and the packing fraction. We also show that the intensity as a function of time-delay can be used to analyze the particle size distribution and packing fraction of an optically thick sample independently of the presence of absorption features. Finally, we propose an all new way to measure the shape of ultra-short pulses that have propagated through a SSM.