Detection of high level carbon dioxide emissions using a compact optical fibre based mid-infrared sensor system for applications in environmental pollution monitoring

A novel and highly compact optical fibre based sensor system for measurement of high concentrations CO2 gas emissions in modern automotive exhaust is presented. The sensor system works based on the principle of open-path direct absorption spectroscopy in the midinfrared wavelength range. The sensor system, which comprises low cost components and is compact in design, is well suited for applications in monitoring CO2 emissions from the exhaust of automotive vehicles. The sensor system utilises calcium fluoride (CaF2) lenses and a narrow band pass (NBP) filter for detection of CO2 gas. The response of the sensor to high concentrations of CO2 gas is presented and the result is compared with that of a commercial flue gas analyser. The sensor shows response times of 5.2s and demonstrates minimal susceptibility to cross interferences of other gases present in the exhaust system