Dual-wavelength Way To Differentiate Fire Smoke Particles And Interfering Particles

Traditional photoelectric smoke detectors alarm simply by detecting light intensityscattered by smoke particles. However, because some atmosphere can also causephotoelectric smoke detector light scattering effect like smoke particles, that will lead tofalse alarm. These particles which cause false alarm are called interfering particles. Themain part of interfering particles is drip particles and dust particles, so it is important forreducing false alarm to differentiate fire smoke, drips and dust correctly.There are some differences in shapes and particle diameter among fire smoke, dripsand dust: drips are spheres while smoke and dust are non-sphere, dust’s diameter is muchlarger than smoke and drips. These differences will causes differences in light scatteringcharacteristics and the light scattering matrix which is able to describe particles’ lightscattering characteristics will also be different.It calculates light scattering matrix of smoke, dust and dips by T-matrix method afterchoosing incident light with two wavelengths. With analysis of average unitary calculationresults, differences among particles’ matrices reflect shapes’ and diameters’ difference tosome extent. One element of unitary matrix turns particles visual differences to numericdifferences. There is a way to turn the element numerical value to logistic value and thenthere is Dual-Wavelength way to differentiate smoke parties, drips and dust with logisticXOR calculation.