Calibration between fiber-optic probe based Raman spectroscopy systems
Caldwell, Brittany Catherine
The present technique to correct for instrument variations between fiber-optic probe based Raman spectroscopic systems is through the use of a NIST tungsten calibrated lamp spectrum. This method does not accurately correct for all sources of variation however, as it only measures throughput of the detection leg. Not accounted for are variation due to source and inline filtering in fiber optic probes. Lamp spectra cannot be taken in all measurement situations due to safety of the emitted light and size of the instrument, adding a second difficulty to the use of this standard. To accurately correct for system variation in all measurement situations, a new method for correction is desired. Presented is a new technique and standard, consisting of a unique colored glass, to correct for instrument variation including detection and source components. This method is practical in all measurement situations and cost effective. Multiple systems were used to validate the technique for both probe and instrument variation. Three samples with unique Raman spectra and background fluorescence were obtained to understand the full capability of the technique and its ability to correct for variation. Spectra were corrected with the gold standard lamp correction method and the glass technique for a comparative evaluation of strengths and weaknesses. The results confirm the ability to use glass as a standard to correct for fiber-optic probe based Raman spectroscopic systems.