An analysis of methods of atmospheric gas concentration retrieving from diode laser measurements

Atmospheric gas tunable diode laser (TDL) monitoring scheme is sensitive, local, real-time and portable. The traditional spectrophotometric methods have more performances for gas analysing, but are slow in response in high spectral resolution scheme and depend on influences by different gas species. Local measurements of small atmospheric gas components concentration (CH4, CO, etc.) with diode-laser spectrometers are widely used in various of science and technical applications. An inverse task is usuallu solved by the correlation method (using all the measurement wavelengths) or other methods (for example, the method of fitting of the recorded spectrum under modelling). Each of these approaches has restrictions on retrieving connected with the features of measurement methods used in practice. This report, the results of the different inverse methods for retrieving the methane concentration from the data of a diode-laser spectrometer working in the NIR spectral range are analyzed. The methane diode-laser detector has a reference cell (with the known methane concentration) and a cross-flow cell (atmospheric air) as shown in Fig.1. The program of control and data processing of measurements is written with help of LabView software.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.