This paper describes improvements to a novel fibre optic methane sensor which has several advantages over previously published fibre optic techniques. As with the earlier method, it is based on a scanning Fabry Perot etalon filter and is self-referencing, requiring only a single optical sensing path and photodetector. A laboratory version of the sensor, employing a white light source, has been constructed and tested, and was found to be capable of detecting 0.01% by volume methane in air, with a response time of approximately 1 second.
J. P. Dakin,
W. F. Croydon,
N. K. Hedges,
"A Fibre Optic Methane Sensor Having Improved Performance", Proc. SPIE 0949, Fibre Optics '88, (21 September 1988); doi: 10.1117/12.947535; https://doi.org/10.1117/12.947535