Performances of a fiber optic Raman system: importance of the interferential filter in art applications

摘要

The great utility of Raman spectroscopy in molecular identification of pigments is well known. Furthermore, the incorporation of fiber optical technology has brought new advantages as compactness, security, weight and price reduction of lasers, and accessibility to analysed object. This is possible thanks to the recent notch and interferential filters, which almost eliminate, respectively, the Rayleigh frequency and both the self Raman spectrum of the fibre and laser plasma frequencies. However, the last has a great dependency on the filter spectral width. In this work, the important role that the quality of the interferential filter plays in the specific case of pigments identification is experimentally shown. Lead yellow pigments (stannate, antimoniate, ternary...) provide very important examples due to the coincidence between a fundamental Raman band of the pigment and some residual plasma frequencies.