Improved Raman Spectroscopy

摘要

Raman spectroscopy is used for determining the characteristics of surfaces or sub-surfaces, such as within a plastic container. The surface is irradiated with two wavelengths, both greater than 1000nm to reduce the effects of fluorescence and with overlapping or adjacent Raman shifted bands, scattered light collected and the Raman spectra generated. The two spectra are combined (i.e. subtracted) to reduce surface absorption effects. Surface offset Raman spectroscopy (SORS) may be used, collecting scattered light at the light source position and a second spatially offset position to produce a sub-surface Raman spectrum at each wavelength. The light sources may be lasers emitting light for example at 1118nm and 1180nm. It may be used for inspection of the contents of a plastic (e.g. HDPE) container.