Fibre-optic Raman probe:

In a fibre-optic probe the laser beam from the source is focused onto input fibres that transport it to the sample. The collection fibres which surround the input fibres in the probe collect a scattered radiation from the sample and send it back to the instrument. It is then directed to a suitable monochromator.

 We need to have means of enhancing the intensities of Raman lines because firstly these lines are intrinsically weak and secondly these get masked by much more intense Rayleigh line. The three techniques employed for the purpose

i)          Resonance Raman Spectroscopy (RRS)

ii)        Coherent Anti-Stokes Raman Spectroscopy (CARS)

iii)       Surface Enhanced Raman spectroscopy (SERS)