High-precision CO2 isotopologue spectrometer with a difference-frequency-generation laser source

A precision laser spectrometer for the detection of CO2 isotopes is reported. The spectrometer measures the fundamental absorption signatures of C-13 and C-12 isotopes in CO2 at 4.32 mu m using a tunable mid-IR laser source based on difference-frequency generation. The spectrometer attains a precision of up to 0.02 parts per thousand for 150 s of averaging. An overall accuracy of 0.05 parts per thousand was obtained when sampling various calibrated reference gases. (C) 2009 Optical Society of America