Study on spectral lines to improve the measurement accuracy of H2O molecular concentration based on TDLAS technology

H2O is an important molecule in the atmosphere, which is closely related to climate change and industrial applications (such as combustion process). The detection of trace water vapor concentration is of great significance in earth ecology and industrial production. Tunable diode laser absorption spectroscopy (TDLAS) inverses the gas concentration by measuring the gas absorption spectrum. The wavelength of the common characteristic absorption peak of H2O molecule is 7181.16 cm-1. The spectral absorption peaks of different wavelengths are analyzed in the paper. It is proved that when 7306.75 cm-1 characteristic absorption peak is used to replace 7181.16 cm-1 characteristic absorption peak for concentration inversion, the influence can be reduced and the measurement accuracy can be improved by combining the target peak with the interference peak.