Based On Mie Scattering Particle Concentration Detection System Key Technology Research Can Be Inhaled

Particle matters is whose size is not more than10microns in atmosphericparticulates, it is made up of a large number of chemical mixtures which possesdifferent sources in the atmosphere, it not only threatens the health of humanbody, and also brings many negative impacts on the atmospheric visibility,environmental factors such as ambient temperature. At present, theconcentration of inhalable particle is an important indicator in atmosphericenvironment monitor, the generating mechanism of particle matters, however isstill in its infancy in our country. Thereby, detecting the concentration ofinhalable particle has a positive impact on all kinds of respiratory diseaseprevention and the improvement of air quality. There are many kinds of methodsdetecting the concentration of particle matters. Contrast with sieving method,sedimentation method, and electrolyte sensing zone method etc. the method oflight scattering has play an important role in the concentration detection ofparticle matters, because of having the advantage of wide applicability, wideresponse range, high precision, short measure time, non-contact etc.The light scattering has many basic theories, such as Fraunhofer and Fresneldiffraction theory, Rayleigh and Mie scattering theory. In this thesis, Miescattering theory are summarized and illustrated in detail, by three-wavelengthmethod which can calculate the average diameter of PM10and PM2.5,a precisetesting instrument which can measure the concentration of inhalable particle atthe atmospheric is designed in combination with the algorithm of distributedfunction. Aim at getting the relative refractive index of inhalable particle, weperformed the computation using optimization algorithm in the CPU afterlimiting the field of real and imaginary part. The dependence of extinction indexwith spectrum is calculated based on Mie scattering theory in this article.Furthermore, the signal of time domain is integrated in the data processing toreduce the effect of error caused by multi-peak of spectra.The PM2.5and PM10are collected simultaneously in particle selection.Three different wave-lengths of lasers are coupled into an optical fiber by coupler (3in1) and pass through the sample cell. The attenuated light is detectedby a PIN. Output of the detector is converted, amplified, displayed and stored byelectronic system. Finally, the data are transmitted and shared in networkthrough the3G wireless module. The average particle size and concentration ofinhalable particle are measured by this device at same time. The technicalspecifications of the detector is verified by experiment, the experimental resultsindicate that the detection sensitivity of system is1μg/m3, the respnsive time ofsystem is approximately90s and it is suitable for measuring particulate matterconcentrations of atmosphere.