A NEW METHOD FOR COLLECTING DIGITIZED DIODE LASER SPECTRA WHICH PROVIDES A VERY ACCURATE FREQUENCY SCALE.
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Date
1989
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Ohio State University
Abstract
A new method of Tunable Diode Laser (TDL) spectrum digitization is presented. While the TDL frequency is slaved to an internally coupled Fabry Perot Interferometer $(icFPI)^{1}$, this interferometer is tuned in a step by step manner. The extrema of a HeNe laser interference pattern trigger periodic temporary stabilization of the interferometer to the HeNe laser frequency. Thus at each step, the infrared spectroscopic data, characterized by a very stable and stationnary frequency, are collected into a computer. This technique is combined with a confocal Fabry Perot etalon, thus providing a frequency scale accuracy of about $3.5 10-5 cm^{-1}$ over a $1 cm^{-1}$ scan. The method is shown to be consistent with high resolution Fourier transform and heterodyne spectroscopy results, based on relative position measurements of $N_{2}O$ absorption lines in the $2220 - 2240 cm^{-1}$ spectral region.
Description
$^{1}$ M. Reich, R. Schieder, H. J. Clar, and G. Winnewisser, Appl. Opt. 25, 130 (1986).
Author Institution: Laser Analytics, inc.
Author Institution: Laser Analytics, inc.