A simple method for evaluation of optical scattering effect on the Raman signal of a sample beneath an Intralipid layer

Optical scattering by biological tissues largely deteriorates the efficiency of the Raman analysis of these tissues. To evaluate the effect of scattering on Raman depth profiles (RDPs), we developed a simple method using a thin-layered sample mimicking real tissues and a conventional Raman microscope. The sample comprised three layers: a silicon wafer, a thin aqueous film containing Intralipid particles as scatters, and a fused silica window; this design was used to mimic real skin tissues quantitatively. The multi-scattering effect, which deteriorates spatial resolution, was clearly observed as broadening of RDPs. Decrease in Raman intensity was also systematically examined as a function of both the concentration of the Intralipid particles and depth of the film, and evaluated using Lambert-Beer's law. The abovementioned observations can be quantitatively explained on the basis of the scattering cross-section and concentration of the Intralipid particles, indicating that the method is useful for the quantification of the deterioration of Raman measurements due to optical scattering.