Sensitivity of spatially-resolved diffuse reflectance to high-order optical parameters

Abstract

Spatially resolved reflectance close to the source is dependent on high-order optical parameters of the media. In order to investigate the influence of high-order parameters on the diffuse reflectance, we define sensitivities of the spatially-resolved diffuse reflectance to the second- and third-order optical parameters. The sensitivity denotes the relative change of diffuse reflectance due to a change in the optical parameter. Expressions of the sensitivities are derived from P3 approximation theory, and numerical analyses are performed. We show that the sensitivity changes with source-detector separation and reaches a maximum in the region between one transport mean free path and two transport mean free paths, and is positive in the region beyond one transport mean free path. The influence of third-order optical parameter on the diffusing reflectance can be ignored in comparison with the influence of second-order optical parameter.