Spatially Offset Raman Spectroscopy

Spatially Offset Raman Spectroscopy (SORS) is a variant of Raman spectroscopy that allows highly accurate chemical analysis of objects beneath obscuring surfaces, such as tissue, coatings and bottles. Examples of uses include analysis of: bone beneath skin, tablets inside plastic bottles, explosives inside containers and counterfeit tablets inside blister packs.

Raman spectroscopy relies on inelastic scattering events of monochromatic light to produce a spectrum characteristic of a sample. The technique usually uses the red-shifted photons produced by monochromatic light losing energy to a vibrational motion within a molecule. The shift in colour and the probability of inelastic scatter is characteristic of the molecule that scatters the photon. A molecule may produce over 10 to 20 major lines, though this is restricted only by the number of bonds and symmetry constraints. Importantly, the spectrum produced by a mixture forms a linear combination of the component spectra, enabling relative chemical content to be determined in a simple spectroscopic measurement using chemometric analysis.