International Comparison of /sup 127/i/sub 2/-Stabilized He-Ne Lasers at /spl Lambda/=633 Nm Using the Third And/or the Fifth Harmonic Locking Technique

An international comparison has been carried out of /sup 127/I/sub 2/-stabilized helium-neon lasers at /spl lambda/=633 nm from the CMI and the BIPM using the beat frequency technique. The lasers were stabilized by the third (THT) and/or the fifth (FHT), harmonic locking technique. Using the FHT, the frequency of lasers is shifted to higher frequencies. An iodine cell designated JM-03 was used to evaluate the frequency shifts produced by weaker components of the rotational-vibrational transition P(33) 6-3 in the mixed molecule /sup 127/I/sup 129/I. Laser comparison shows that the frequencies of components d, e, f, g of the R(127) 11-5 of the molecule /sup 127/I/sub 2/ are very strongly influenced by the weaker spectrum of components of the mixed molecule.<>