Compact optical access implementation for high-speed thermometry in a motorcycle engine

An optical sensor using near-infrared (NIR) absorption spectroscopy to measure crank angle-resolved temperature and the mole fraction of water vapor at the intake manifold of a motorcycle engine is presented. The sensor aims to produce a detailed database of operating parameters for building computational models, using tools like GT Power, and to analyze valve backflow during high rpm runs (over 4500 rpm). We demonstrate high-speed (10 kHz) thermometry using a compact optical access strategy, optimized using ray-tracing simulations. Additionally, the entire optical access was designed for installation from one end, allowing for easy integration with the rest of the test setup.