Raman spectroscopy gives details about the molecular structure of samples and may identify samples (mineral, pigments) by the spectral bands which correspond to characteristic bond vibrations.

In the present study, a compact Raman microspectrometer, with excitation source a diode laser, emitting at 786 nm was used. The beam where focus on the sample surface by an objective lens which provide focusing of the beam in an area around 50 μm.

The scattered Raman radiation is collected through the focusing objective and sent through an optical fiber to a compact spectrograph and CCD detector, which record the spectrum.

A high resolution colour camera offer a very clear view of the area under investigation.