Determination of the absolute oscillation frequency of the 3s2→2p4 transition in a helium-neon laser

The optical frequency of the 3s₂→2p₄ transition in a He-Ne laser was determined by comparison with a secondary radiofrequency standard operating at ν_st = 1999.3865 MHz. The measurement method was analyzed and the frequency deduced from a series of such measurements was found to be 473, 612, 162±23.8 MHz.