The development of a rugged, compact gas spectrometer using a sub-THz waveguide

We present a novel low-cost and compact method for detecting trace gases using their absorption features in the sub-THz region. Conventionally, work in this area uses free space quasi-optics which have inconveniently large and potentially costly instrumentation. This is due to the drawbacks of the optical setup which require both long beam paths and large optics in this frequency range. Instead, we have developed a novel system that confines the radiation to a specially designed waveguide meaning long pathlengths (and therefore high SNR) can be achieved in a relatively small instrument and no optics or alignment are required. A flow of gas is introduced into the waveguide which changes the spectral transmission loss. This technology has been demonstrated in the lab and can be applied to any gases with absorption features in the sub-THz region. A deployable instrument has been completed, and we aim to engage in field testing in the near future.