Optical Cavity Enhanced Real-Time Absorption Spectroscopy Of Co2 Using Laser Amplitude Modulation

We present a spectrometer based on the cavity enhanced amplitude modulated laser absorption spectroscopy (CEAMLAS) technique for measuring molecular gas absorption. This CEAMLAS spectrometer accurately measured a CO2 absorption line at 1572.992 nm with effectively 100% measurement duty cycle. It achieved an absorption sensitivity of 5.2 x 10(-9) Hz(-1/2) using a linear Fabry-Perot cavity with a modest finesse of approximate to 1000. We also used the spectrometer to perform preliminary measurements of the C-13/C-12 isotopic ratio in CO2, yielding an isotopic signature delta C-13 of -83 +/- 9 parts per thousand for our CO2 sample. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.