Simulation and measurement of carbon dioxide exhaust emissions using an optical-fibre-based mid-infrared point sensor

A novel optical-fibre-based sensor for measurement of CO₂ gas emission concentrations in exhaust systems of a motor vehicle is reported. The sensing principle is based on open-path direct absorption spectroscopy in the mid-infrared range. The sensor system comprises of low cost and compact mid-infrared components, which make it suitable for insertion into the exhaust system of automotive vehicles. The sensor utilizes a calcium fluoride CaF₂ narrow band pass (NBP) filter for detection of CO₂ gas without cross-sensitivity to other gases present in the exhaust system. Furthermore, it can be integrated into the mechanical and electronic interface systems of existing vehicles without any problems.