The emission from dense plasmas produced by a Q switched ruby laser pulse focusing on plane targets of the elements Be, C and N has been observed in the vacuum ultraviolet at various distances from target surface. For recording the emission spectra an intensified photodiode array and an optical multichannel analyzer have been implemented. Very broad lines of the type △n=l of the H-like He-like and Li-like ions arising from relatively high principal quantun number n appear prominent in the spectra. And according to the ion quasistatic approximation theory the electron densities of the plasmas as the function of the distances from the target surface have been derived.