On Gas Detection and Concentration Estimation via Mid-IR-based Gas Detection System Analysis Model

Due to recent development in laser technology and infrared spectroscopy, Laser-based spectroscopy (LAS) has been used in a wide range of research and application fields. A particular application of interest is mid-IR laser-based gas detection systems for health and environment assessment. The NSF-ERC Mid-Infrared Technologies for Health and Environment (MIRTHE) project has engineers and researchers from different areas. As a participant in MIRTHE, we study the performance analysis and improvement possibilities of the integrated sensing system. Herein, we have improved the developed statistical analysis model, and then used our statistical analysis model for a generic mid-IR pulsed-laser gas detection system to predict trace gas detection and concentration estimation performance, and their sensitivity to system parameters. Based on PNNL (Pacific Northwest National Laboratory) data and the Beer-Lambert law, we defined three main spectral peaks of a trace gas for detecting target gas and evaluate 3-peak joint detection performance in terms of PD vs PFA. For concentration estimation we used the relationship between gas transmittance β, molar absorptivity ε, concentration c, the sample-mean measurement, xN, from the photo-detector, and number of samples, N, as the basis. Using the standard confidence interval method, we evaluated estimation reliability, and then analyzed estimation errors. Analytical gas detection and concentration estimation results are presented for 17 trace gases at 1 ppm and 1 ppb concentrations