Spectral concentration

The laser is capable of emitting radiation at an extremely precise frequency: the relative precision can reach 1014. It is therefore a reference of frequency that can now be quite easily linked to the frequency standard of the caesium clock. Thanks to lasers, spectroscopy has made enormous progress. The spectral fineness of laser sources now enables atoms to be manipulated and to be cooled down. Thus, knowledge in optics can be transposed to the study of atoms (atomic optics).