Experimental determination of effective light transport properties in fully anisotropic media

TL;DR

This paper introduces an improved experimental method to accurately determine the anisotropic light transport properties of materials by combining transient transmittance measurements with a generalized Monte Carlo model, addressing previous modeling challenges.

Contribution

The paper presents a novel approach for measuring the light transport tensor in anisotropic media, enabling precise characterization of direction-dependent scattering coefficients.

Findings

Accurate determination of anisotropic light transport properties in PTFE tape and paper.

Significant deviations occur when anisotropy is neglected in optical characterization.

The method improves the reliability of optical measurements in anisotropic materials.

Abstract

Structurally anisotropic materials are ubiquitous in several application fields, yet their accurate optical characterization remains challenging due to the lack of general models linking their scattering coefficients to the macroscopic transport observables, and the need to combine multiple measurements to retrieve their direction-dependent values. Here, we present an improved method for the experimental determination of light transport tensor coefficients from the diffusive rates measured along all three directions, based on transient transmittance measurements and a generalized Monte Carlo model. We apply our method to the characterization of light transport properties in two common anisotropic materials - polytetrafluoroethylene (PTFE) tape and paper - highlighting the magnitude of systematic deviations that are typically incurred when neglecting anisotropy.