Backscattering of light by a multiple scattering medium

Abstract

In the theory of radiative transfer, the searchlight problem seeks to determine the light transmitted and backscattered by a plane-parallel multiple scattering medium due to an infinitesimal pencil beam of light incident on it. A special case of this problem corresponds to backscattering by an infinitely thick half-space. For many applications such as biomedical optics, this half space problem is fundamental for modeling non-invasive measurements. It provides valuable insight into how specific optical properties of the scattering medium influence possible measurements of backscattered light. It is well known that at large spatial scales, a strongly scattering medium leads optical diffusion from which one can recover large-scale properties of the medium. Several recent works have sought to identify regimes of backscattering where one can recover information about the scattering phase function which provides information about small-scale features of the scattering medium. We present some recent results that identify asymptotic limits in which backscattering is governed by low-order scattering. The first corresponds to spatial frequency domain imaging at high spatial frequencies. The second corresponds spatial regions near the center of a beam of finite width that is the smallest length scale in the problem. For both of these limits, we apply the first-order scattering approximation, evaluate its properties, and validate them with numerical computations. We propose how these asymptotic theories can be used to address those questions regarding the small-scale features of a multiple scattering medium.

Date
May 31, 2024 1:00 PM
Event
Seminario GMNA
Location
Sala de Seminarios del Departamento de Matemáticas (2.2.D08)