Monte Carlo method for polarized radiative transfer in gradient-index media

TL;DR

This paper introduces a Monte Carlo method to simulate polarized light transfer in gradient-index media with planar ray trajectories, accounting for curved paths and scattering effects, validated through various test cases including atmospheric conditions.

Contribution

The paper presents a novel Monte Carlo approach that solves the ray equation to second order, enabling accurate simulation of polarized radiative transfer in gradient-index media with curved trajectories.

Findings

Atmospheric refraction significantly affects long-distance polarized light transfer.

The method accurately models scattering in gradient-index media.

Validation confirms the method's effectiveness across different media types.

Abstract

Light transfer in gradient-index media generally follows curved ray trajectories, which will cause light beam to converge or diverge during transfer and induce the rotation of polarization ellipse even when the medium is transparent. Furthermore, the combined process of scattering and transfer along curved ray path makes the problem more complex. In this paper, a Monte Carlo method is presented to simulate polarized radiative transfer in gradient-index media that only support planar ray trajectories. The ray equation is solved to the second order to address the effect induced by curved ray trajectories. Three types of test cases are presented to verify the performance of the method, which include transparent medium, Mie scattering medium with assumed gradient index distribution, and Rayleigh scattering with realistic atmosphere refractive index profile. It is demonstrated that the atmospheric refraction has significant effect for long distance polarized light transfer.