Expanded Wavelength Nephelometry for Improved Particle Detection

Using optical particle scattering/absorption measurements combined with interdigitated corrosion sensors, a novel measurement system has been developed by American Ecotech.  This sensor measures the real-time concentration of aerosolized chlorides (salt) in the air. However, large particles are difficult to measure with traditional nephelometry (using visible wavelengths). This is because they do not interact as readily with short wavelength light. Resolution can be improved by increasing the wavelength to better match the particle sizes of interest. This project aims to increase the operational wavelength of our commercial nephelometer from 650 nm to both 1064 nm and 1550 nm.  This will make the system better able to distinguish airborne sea salt crystals which range between 0.8-10 µm in most coastal regions. Increasingly heightened life cycle management costs necessitate this type of accurate, real-time, easily deployable, robust, condition-based monitoring solution. The data generated by this system will be fed into an AI/ML model being developed by MIT Lincoln Labs that predicts corrosion behavior. This software tool will alert aircraft maintainers when contamination levels become too high.  An alert will trigger maintenance procedures such as washing and inspections which will help reduce overall DAF sustainment costs. The 1064nm wavelength has the added benefit of being used in most Directed Energy weapons and its use will give additional information on the effectiveness of these weapons in the field.