Optical cavity enhanced real-time absorption spectroscopy of CO2 using laser amplitude modulation

Abstract

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 1572.992nm with effectively 100% measurement duty cycle. It achieved an absorption sensitivity of 5.2×10-9Hz-1/2 using a linear Fabry-Perot cavity with a modest finesse of 1000. We also used the spectrometer to perform preliminary measurements of the 13C/ 12C isotopic ratio in CO2, yielding an isotopic signature δ13C of -83±9‰ for our CO2 sample. © 2014 Author(s).