Frequency stabilization of internal-mirror helium-neon lasers

A simple and inexpensive frequency stabilization system of a helium-neon two-mode laser with an internal mirror plasma tube is described. The stabilization depends on the comparison of the light intensities of the two operating longitudinal modes. The corresponding frequencies of the modes are symmetrized about the emission line of neon at the transition 3s(2)-2p(4). Experimental results are given. The relative uncertainty of the frequency stabilization is less than 1 part in 10(7).