Light source distribution and scattering phase function influence light transport in diffuse multi-layered media

Abstract

Red and near-Infrared light is often used as a useful diagnostic and imaging probe for highly scattering media such as biological tissues, fruits and vegetables. Part of diffusively reflected light gives interesting information related to the tissue subsurface, whereas light recorded at further distances may probe deeper into the interrogated turbid tissues. However, modelling diffusive events occurring at short source-detector distances requires to consider both the distribution of the light sources and the scattering phase functions. In this report, a modified Monte Carlo model is used to compute light transport in curved and multi-layered tissue samples which are covered with a thin and highly diffusing tissue layer. Different light source distributions (ballistic, diffuse or Lambertian) are tested with specific scattering phase functions (modified or not modified Henyey-Greenstein, Gegenbauer and Mie) to compute the amount of backscattered and transmitted light in apple and human skin structures. Comparisons between simulation results and experiments carried out with a multi-spectral imaging setup confirm the soundness of the theoretical strategy and may explain the role of the skin on light transport in whole and half-cut apples. Other computational results show that a Lambertian source distribution combined with a Henyey-Greenstein phase function provides a higher photon density in the stratum corneum than in the upper dermis layer. Furthermore, it is also shown that the scattering phase function may affect the shape and the magnitude of the Bidirectional Reflectance Distribution (BRDF) exhibited at the skin surface.

Deep skin homogeneity and light diffusion: An accelerated Monte Carlo model for in vivo skin characterization and consumer perception

“…This Monte Carlo model contains a spectral dispersion of the skin optical absorption and scattering coefficients for each panellist. The depth and wavelength dependence of the anisotropy factor g is also included [21][22][23].…”

Light scattering in thin turbid tissue including macroscopic porosities: A study based on a Monte Carlo model

“…If an apple flesh tissue immersed in water (such as considered in these previous studies [40,41,43]) is strongly porous, apple skin tissue can be approximated as a classical multilayer turbid medium [44], whose matter density is higher than the flesh one. In the same manner, the results related to Fig.…”

Possibilities of Diffuse Reflectance Spectroscopy in Determining and Operational Control of the Optical Properties of Finely Dispersed Scattering Media

“…The problem of non-destructive testing of various materials and media is multifaceted and has several directions for its solution. Optical spectroscopy is widely used in the analysis of media composition [1][2][3]. A fairly new direction in the optical control of inhomogeneous, strongly scattering media is the spectroscopy of back diffuse reflection of light radiation with spatial resolution [4][5][6][7].…”