By Yihong Wang, Hui Lu

Differential optical absorption spectroscopy (DOAS) technology enables accurate real-time monitoring of the concentration of flue gas components and is an effective means of controlling flue gas pollutant emissions at source. In DOAS systems, light source intensity variation is an important factor affecting the long-term reliability of the measurement. To address this issue, a novel calibration-free DOAS inversion algorithm is proposed, which uses a domain broadband cross-section to normalise the narrowband cross-section of gas characteristic absorption, thus obtaining an equivalent absorption intensity parameter, αeq, that is not affected by light source intensity variations. Compared to conventional algorithms, this algorithm does not require complex calculations such as polynomial fitting and signal filtering and is easier to implement in hardware.