Multiwavelength sensing of smoke using a polychromatic LED: Mie extinction characterization using HLS analysis

A multiwavelength-sensing scheme using a polychromatic light-emitting diode has been developed for monitoring smoke to allow combustion material to be characterized. Spectral analysis uses HLS chromaticity parameterization to examine the interaction effects on the transmission of polychromatic light due to airborne aerosol/particles. The effects of wavelength and sample are investigated, and it is shown that, by using HLS analysis, it is possible to uniquely identify a combustion material by variations in lightness and saturation over a range of hue values. Lightness and saturation are shown to follow a distinct locus unique to the smoke from the combustion material, although the effect of fuel-oxygen mixing ratios have not been investigated and the data set is limited to two proof-of-concept case studies. The technique may, therefore, be applied to fire detection in inaccessible or remote areas (e.g., chemical plant, aircraft engines, etc.) where the type of response may be critical and dependent on combustion material. It may also potentially be used to identify liquids from their aerosol.