There is described a method for performing a Raman spectroscopy measurement on a sample. The method generally has sequentially illuminating an area of said sample with first and second excitation signals, said first excitation signal being slightly spectrally spaced-apart from said second excitation signal, resulting in said area sequentially emitting first and second emission signals; upon receiving said first emission signal, measuring a first intensity value being indicative of optical intensity of said first emission signal within at least a detection band; upon receiving said second emission signal, measuring a second intensity value being indicative of optical intensity of said second emission signal within said detection band; and performing said Raman spectroscopy measurement by comparing said first intensity value to said second intensity value.