Abstract

Precision optical spectroscopy of molecular lines as, e.g., in I₂ or Te₂ molecules, with reference to iodine stabilized He–Ne lasers has been performed by many groups and is still of utmost importance for the calibration of optical spectra. Of particular interest are, of course, narrow optical reference lines in the vicinity of transitions which are used for time and frequency applications, such as the He–Ne laser transition near 633 nm or, more recently, the 1S–2S transition in atomic hydrogen near 486 nm.¹

© 1994 Optical Society of America