Applicability of blue/UV laser diodes for the measurement of vaporized fuel fluorescence around stoichiometric concentrations

A fluorescence-based fiber-optic probe is implemented for use with a blue/UV laser diode to form a rugged, nonintrusive fuel sensor. Measurements are obtained from a test vessel controlled to replicate the temperature and pressure environment in a typical combustion engine. A fuel containing a specific polycyclic aromatic hydrocarbon (perylene, C20H12) is used to obtain wavelength resolved information and concentration variation characteristics. Emission intensity is examined in atmospheres with and without oxygen at pressures from 1 to 10 bar. The signals from a retail gasoline fuel present a greater challenge as they result from a complex mixture of hydrocarbon components. Detection of gasoline vapor concentrations in the range of 4% to 125% of stoichiometry is demonstrated.