Realization of a methane leaks detector for roads inspection

We present our novel methane leak detector using distributed feedback diode lasers emitting at the wavelength of 1.651 micron. It has been designed to operate on board of small vehicles, for the detection of methane leaks from distribution pipes under the roads. The main features of this detector are range: 1-10000 parts per million, resolution 1 part per million-10% according to the reading, selectivity greater than 10000, time resolution 1 second or better. The analyzer is based on the Beer-Lambert law for light absorption. Two detection techniques are adopted: two-tone frequency modulation spectroscopy for low concentrations, and direct absorption for high concentrations.