Abstract:

We analyze the impact of temperature variation on the spectral characteristics of methane absorption line and the concentration measurement of methane gas with the absorption lines in R3 transitions of 2v3 band of methane at 1 653.72 nm. We detect methane gas concentration with first harmonic signal based on tunable diode laser absorption spectroscopy and wavelength modulation spectroscopy. We also suppress the interference of temperature variation on detection accuracy by temperature compensation. Experimental results show that the methane detection system is stable. Its system measurement error is within 1% after the calibration of temperature compensation coefficient, so its system detection accuracy can be effectively improved.

Key words: tunable diode laser absorption spectroscopy, wavelength modulation, first harmonic, temperature compensation