Design of a fibre optic multi-point sensor for gas detection
Sensors and Actuators B: Chemical
Volume 51, Issues 1–3, 31 August 1998, Pages 227–232

We report the design of a multi-point fibre optic methane sensor using a DFB laser source with a branched fibre network and micro-optic cells. Measurements are performed through derivative spectroscopy, with line scanning and digital signal processing, to give sensitivities down to a few ppm metre. The form of the derivative signal obtained from the system is modelled theoretically and compared with the experimental signal. The main limitation in the signal to noise ratio of the system is due to interference effects (etalon fringes) from the cells and we show how these effects may be minimised.