Four-color fiber-coupled mid-infrared laser-absorption sensor for temperature, CO, CO, and NO at 5 kHz in internal combustion engine vehicle exhaust.

A mid-infrared (MIR) laser absorption spectroscopy (LAS) sensor was developed for temperature, CO, NO, and measurements at 5 kHz in engine-out exhaust. It used fiber-coupled quantum cascade lasers (QCLs) for measuring CO and NO, and an interband cascade laser (ICL) for measuring . Validation tests in a heated gas cell confirmed that the LAS measurements of CO, , NO, and temperature are accurate to within 4.