Optical sensors for automotive engine-research applications

In this work, we present applications of optical sensors for crank angle resolved determination of air-fuel ratio (lambda-value) during stratified operation of internal combustion engines. Different types of sensors for measurement of the local lambda-value at the spark plug position and the mixture temperature with high temporal resolution are demonstrated. The sensors are based on mid-infrared (MIR) absorption, spontaneous Raman scattering (SRS) and tunable diode laser absorption spectroscopy (TDLAS). The sensors are incorporated into modified spark plugs in order to allow operation in production engines under realistic conditions