Study On A Multimode Laser Correlation Spectroscopy Technology Based Elemental Mercury Analyzer

Air quality is closely related to people's lives,and now people have more and more attention to air pollution problems.Mercury is persistent,highly bioaccumulative,highly biotoxic and easily migratory.Mercury emissions can cause serious environmental pollution,endangering human and ecological health.China is a major mercury emitter.Based on multimode diode lasers,a set of low cost continuous monitoring system for elemental mercury was established.Mercury has a strong absorption at 253.7 nm.In this paper,two low cost multi-mode diode lasers with wavelengths of 680nm and 405nm are used.And a continuous monitoring system of elemental mercury is built by using the sum frequency effect of BBO crystal.The direct absorption spectrum of elemental mercury is obtained by modulating the injected current to change the wavelength of the generated laser.The correlation spectroscopy technique is used to counteract the influence of the absorption line change caused by the multimode laser mode jump.The algorithm of multiple linear regression is used to realize automatic data analysis and processing.When the integration time is 80s,the detection limit is better than 0.1?g/m2,which meets the needs of industrial monitoring.The repeatability and fluctuation of the system indicate that the continuous monitoring technique of elemental mercury proposed in this paper has a wide application prospect in the field of industrial mercury emission monitoring.