The Raman wave-number shift for scattering at oxygen molecules is almost exactly 2/3 of the nitrogen Raman shift. This is used to build up a chain of three consecutive laser emission lines separated by 1/3 of the nitrogen Raman shift. It is shown that it is possible to determine aerosol extinction and backscatter coefficients without a priori assumptions from the received Rayleigh-Mie and Raman (oxygen and nitrogen) signals.