Frequency stabilized 543 nm He-Ne laser

Summary form only given, as follows. Saturated absorption signals with good S/N of the hyperfine structure of the lines R(12)26-0 and R(106)28-0 of /sup 127/I/sub 2/ in external cells were observed and used to lock the frequency of 543 nm He-Ne laser with the third harmonic technique. The two mode balance technique, by heating or cooling laser tube, was used for stabilizing the 543 nm He-Ne laser frequency. We prefer the latter.