Study On Dust Concertiation Measurement Technique Based On Optical Back-Scattering

As the industrial and agricultural development, especially in industrial development, the hazards of dust have also become increasingly serious. China is a big country of coal, where the coal is about 75 percent in the total energy. In this situation for quite a long period of time there will be no fundamental change. The direct burning of a large number of coal decisions to China's air a coal-burning pollution. Many cities are long-term high in the total suspension of particles.Suspended particles in the atmosphere pollutants, particularly small particles, damage greatly on human health. It is the formation of various respiratory diseases. It also has serious implications on the environment. It is important to governance suspended particles of pollutants for the protection of nature and human. The study resolves issues surrounding the measurement of the concentration of dust. From the theory expounded the feasibility of measuring the concentration of dust by back-scattering methods. It has the analysis of the characteristics of back-scattering through theoretical analysis and MATLAB simulation. By measuring in perspective for the post to 180°, the light intensity of back-scattering can get to the 0.4 percent of all. The back-scattering of proportion will not change with it, when the size parameter is larger than three. The intensity of the back-scattering is proportional to the concentration of dust, but inverse proportion to the receiving distance.Measuring instruments was designed, including the chamber, the circuit, such as optical design. Modulation of the laser line based on the number lock-in technology design center frequency of 110 Hz lock-in amplifier, receiver signal demodulator. The apparatus has the ability to extract weak signals from a strong noise background.