The New Measurment Trace Gas Concentration System Of Cw-crds Base On The Effects Of Sagnac

The poisonous, harmful, combustible and explosive gases generated during the process of petrochemical industry, mineral exploitation, energy development and biotechnology have a strong impact on the environment of atmosphere, living condition and sustainable development ability. Therefore, the real-time concentration detection of these gases is very important. Traditional gas concentration measurement methods complete the real gas concentration detection mission to some extent,but the detecting precision of those methods is low,it can not meet the current needs.In this paper,a novel high accuracy gas concentration measurement system is proposed and studied.The main content includes:First, the principles of gas absorption, the measurement principle of cavity ring-down and multiple beam interference is researched.Secondly, a new trace gas concentration measurement system of continuous wave(cw) cavity ring-down spectroscopy(CRDS) is proposed. In this system, the fiber loop based on the Sagnac effects served as a reflector and formed a resonator with a high-reflectivity reflector. It can achieve the reflectivity of the resonator tunable. On this basis, the theoretical analysis and derivation of fiber loop's Sagnac effect and the measurement principle of cavity ring-down are proposed, meanwhile we can obtain the formula of measurement of the trace gas concentration based on CWCRDS and influence of fiber loop rotational speed to the trace gas concentration measurement system.Finally, the relationship between reflectivity and fiber loop rotational speed is obtained via the experimental simulation, and so the reflectivity and cavity ring-down graphs. the ring down time of CO2 with different concentration was obtained via experiment, and the results show that with the higher concentration, the stronger absorption and the shorter ring-down time. The system filter the noise of photoelectric detector by using mathematical morphology filtering method and the excellent effect can be achieved.The results show that the proposed system can provide a certain applcation value to the gas concentration measurement.