Gas leak detection by measuring dilution of ambient air with differential optical dispersion spectroscopy of oxygen.

Gas leak detection is one of the most vital issues in the mining and energy industries. Despite many highly specific and sensitive laser-based spectroscopic systems available on the market, the universal optical gas leak detector is still unattainable. In this paper we demonstrate the laser gas sensing setup capable of indirect detection of virtually any gas leaks using differential optical dispersion spectroscopy of oxygen near 761 nm. A semi-fiber interferometric setup with two multi-pass gas cells yields a signal proportional to the difference in O concentrations between two equal optical path length Herriott multipass cells, which is used to detect leaks of the non-absorbent nitrogen by sensing the dilution of atmospheric oxygen. This new kind of sensor could become a substantial contribution to developing gas-related industries, such as hydrogen fuel storage and transmission.