The article below describes a new proto-type laser that's able to detect methane gas by measuring the light frequency left after the methane absorbs a specific amount. In theory, can an augmented laser system be used to detect CO? Also, what are some state of the art gas detection systems in place today? Ever build your own?
"The system uses laser-based remote sensing technology called DIAL. Laser pulses are emitted with alternate frequencies, one of which is absorbed by the methane. The methane concentration is measured by observing the difference between the amounts of light scattered back to the detector. The laser system will then be swept through a circle to determine the methane concentration over a wide area."