Fuel contamination can be problematic to thermal engine operation, potentially causing engine failure, which may result in the loss of equipment and/or people. The in-line monitoring system designed by our team is based on scattering and imaging methods, and can detect particulate matter and condensed water in the fuel. We propose a refinement of this system to improve detection and sizing reliability, as well as reduce the overall dimension and power consumption of the instrument. This proposal aims at investigating new imaging methodologies to extend the detection capabilities of the instrument under different particle types. Improvements in image processing routines are also planned to take advantage of the new imaging capabilities. As part of the feasibility study, experiments will be carried out to confirm the scattering calculations and assumptions necessary to extract fuel contaminants concentrations. Optional tasks include integrating the scattering methods with the imaging size distribution information toward more accurate concentration measurement and evaluating the potential of a capacitance probe to detect large water presence in the fuel stream.