Computer modelling of the optics of a dispersive Raman spectrometer

The availability of small solid-state lasers, efficient CCD detectors and compact optics has permitted the development of portable Raman spectrometers, which are of great interest for some applications, like cultural heritage or geochemistry. Some of them are 'home made' designs built by combining different elements that are commercially available. In the design phase of these instruments it is of great help to use computer tools, like ray-tracing, that permit the calculation of the spectrometer's performances, and the selection and optimization of the most suitable design. In this paper, we present a ray-tracing study of a laboratory dispersive Raman spectrometer performed with a freely available software package. We calculate the instrumental functions, resolving power, resolutions, aberrations, etc and benchmark some of the results with experimental values. We demonstrate the suitability of these codes for modelling Raman dispersive spectrometers, and their utility, not only in the design phase, but also during the operation of the spectrometer in order to check if it works close to the theoretical performance.