Signal processing method of ambient trace-gas monitoring with tunable diode laser absorption spectroscopy

Abstract

Tunable diode laser absorption spectroscopy (TDLAS) is a new method to detect trace-gas qualitatively or quantificationally based on the scan characteristic of the diode laser to obtain the absorption spectroscopy in the characteristic absorption region. It needs to combine with a long absorption path in the ambient trace-gas measurements. TDLAS has a significant advantage not only in sensitivity but also in rapidity of response. It has been widely used in many atmospheric trace-gases detection, ground trace-gas detection and gas leakage detection. On-line signal processing is necessary to most trace gas monitor. In this paper, data processing method for retrieval of gas concentration, as well as the wavelength alignment algorithm based on correlation detecting technique is described, realizing the aim of wavelength alignment between the standard signal spectral line and the measurement signal spectrum. So the precision of the retrieving system is improved satisfactorily.