Study on Fiber Loop Ring-Down Spectroscopy Application in the Measurement of Dust Concentration

In order to realize high-precision measuring of dust concentration, a new method which combines with fiber loop ring-down spectroscopy on the basis of transmission method was proposed. The dust concentration measuring system was constructed. The principle of measurement was introduced. Erbium-doped fiber amplifier can adaptively compensate for light path loss, dust concentration is a single-valued function of the ring-down time and is measured by analyzing the ring-down time of cavity. Attenuation coefficient was deduced, extinction coefficient was also analysed. Compared to traditional system based on transmission method, the time is needed to be measured in the new system which improves the sensitivity especially in low concentration, laser pulse is adopted as light source which is immune to fluctuation of source intensity. Finally, the experiments of corn dust concentration measurement were performed with the system. The results were compared with the ones which transmission method measuring instrument measured, the feasibility and advantage of this system are verified.