Multi-optical parameter simulation of spatially offset Raman spectroscopy

Abstract

Spatially Offset Raman Spectroscopy (SORS) has extensively been studied as a non-invasive technique that can detect the internal composition below the surface of turbid samples. A critical application of SORS is to identify unknown materials behind a highly scattering obstacle, such as plastic containers. The mechanism of SORS can be generally demonstrated as the photon migration theory; the Raman photons inside deeper samples are more likely to propagate laterally. However, a comprehensive view of the SORS mechanism still needs to be improved. In this work, a numerical simulation was carried out by the Monte Carlo algorithm to investigate the characteristics of SORS being affected by the various optical properties of materials, such as scattering coefficients, absorption coefficients, and refractive index. The key characteristics of SORS, such as detection depth, optimal offset, and signal intensity, were systematically analyzed in a monolayer medium and a bilayer medium. These findings provide important additional information on SORS theory and have important implications for the development of SORS as a reliable analytical tool in various fields, including biomedical research and environmental monitoring.