Composition Analysis of Scattering Liquids Based on Spatially Offset Visible-Near-Infrared Spectroscopy

Spatially offset visible near-infrared (VIS-NIR) spectroscopy was used to analyze of chemical compositions of the scattering liquids in the visible and near-infrared region from 530 to 930 nm. An experimental setup was designed based on a supercontinuum white-light laser source, an electrically controlled translation stage, and a high-performance spectrometer. The spatially offset spectra of the scattering liquids (composed of diluted Intralipid (R) 20% in distilled water) were measured at 24 sequential positions in the radial distribution from the incident light. A partial least squares regression method was applied to obtain the Intralipid concentration from the spatially offset spectra. The results showed that the prediction accuracy of the Intralipid (R) concentration obtained from the spectra collected at multiple sample points was better than that obtained from the spectra collected at a single sample point. The coefficient of determination in the prediction set is 0.9835 at the optimized number of sample points.