Strategies for Passive Sensitivity Improvement of NDIR Ethylene Gas Detectors

Three sensitivity improvement strategies for non-dispersive-infrared (NDIR) ethylene gas detectors were defined and examined: the application of low-cost Fresnel lenses, usage of a conically shaped measurement chamber and a simple digital signal processing lead to a seven times better IR-radiation efficiency compared to a system configuration without consideration of these methods. The approaches don't affect IR-detectors, IR-sources or the optical pathway and thus, the methods can be called "passive". It was shown that usage of lock-in amplifiers is not necessary to achieve good sensitivity results and noise equivalent concentrations of about 6 ppmv. (C) 2011 Published by Elsevier Ltd.