A method for the measurement of the concentration of methane is experimentally demonstrated. The broad light source is filtered by using a Fabry–Perot filter, whose wavelength peaks are matched with the methane absorption lines. The matched guided light is absorpted by the methane in the gas cell, which is coated with a film with 100% reflectivity. Therefore, the guided light is reflected a number of times and the sensitivity of the sensor is increased. The experimental results show that a resolution of 0.091% is achieved. In addition, due to the matched wavelength peaks, the influence of the interfering gas can be removed by using the proposed method. Compared with the conventional method, the proposed method possesses low cost, high sensitivity, and high stability.
"High finesse Fabry–Perot filter for the measurement of methane gas by using multiline absorption spectroscopy," Optical Engineering 53(2), 024103 (14 February 2014). https://doi.org/10.1117/1.OE.53.2.024103