Raman Shift Calibration of a Compact Multichannel Spectrometer

Calibration of the Raman shift scale of a compact spectrometer with a charge-coupled device (CCD) array detector is examined. Argon and neon line spectra are used as wavelength standards, and a shift standard is used to track changes in the wavelength of the doubled Nd:YAG laser line. A method is described to introduce controlled shifts of spectra relative to the detector elements. Excellent precision, on the order of 0.05 cm⁻¹, is achieved in measuring Raman shift values over a period of several weeks. The abscissa accuracy, examined with the use of both Raman lines of known shift and atomic line wavelengths, is considerably poorer than the precision. The likely origins of this discrepancy are discussed.