COMPACT RAMAN SPECTROMETERS - DATA HANDLING METHODS

Measurements have been made on a compact dispersive Raman spectrometer of the type often proposed for on-line measurements. Quantitative use of the details of spectra that are produced by this system require di fferent data treatments than those which have been described for longe r-focal-length instruments. The data sets are sparsely sampled, and th ey cover a wide spectral window. Owing to sparse sampling, spectra as recorded have the appearance of piecewise linear approximations. It is necessary to interpolate additional data points in order to observe d etails of peaks, such as exact positions of maxima. With wider spectra l windows, procedures for calibration of the wavenumber axis which hav e been previously described do not meet our performance criterion: an accuracy of 0.1 cm(-1) or better. A model that involves a fifth-order polynomial is needed. On the basis of the performance of this model, a tomic lines which give satisfactory results when used as wavenumber re ferences have been identified. Details of a self-modeling procedure fo r removal of broad-band spectral interferences are described, and its performance is demonstrated.