Evolution of Raman Spectroscopy for Cultural Heritage: advanced prototypes

The technological evolution of Raman Spectroscopy for increasingly effective applications in Cultural Heritage field is the topic of the research carried out over the last few years at ISPC Raman Laboratory in collaboration with the Rutherford Appleton Laboratory and the University of Cincinnati [1, 2]. Significant modifications to a commercial micro-Raman instrument led to the development of a benchtop prototype with high lateral and spectral resolution coupled with depth sensitivity and 3D mapping capabilities. Three micro-SORS variants (defocusing, internal beam-steered and point-like) are integrated in the prototype enabling the system to be easily adapted to fit specific applications efficiently. The coupling of micro-SORS with different imaging/mapping modalities (conventional, StreamLine and StreamHR) is paving the way for studies of high-resolution molecular distribution of compounds within volumes in art objects. Moreover, an external horizontal probe permits the non-invasive investigation of large objects too. The in-house portable prototype is designed for a rugged, effective detection of Raman signals both in conventional and spatially offset geometries with high spectral and spatial resolution. This feature is achieved by using a linear fiber bundle to conserve the offset information on the detector, permitting simultaneous acquisition of Raman photons emerging from the surface and subsurface in separate spectra. Different designs and applications to case studies in Cultural Heritage will be presented and discussed.