TDLAS (Tunable Diode Laser Absorption Spectroscopy)

TDLAS is an optical gas-sensing technique that measures the concentration of a target gas - for pipeline work, most often methane - by tuning a laser to a wavelength the gas absorbs and measuring how much light is lost across a path. Because it responds to a specific absorption line, it is highly selective for methane and largely immune to interference from other gases, which makes it well suited to airborne and handheld leak surveys. Its principal limitation is that it reports an integrated column concentration along the beam path, so it confirms that methane is present between the sensor and a surface but does not by itself localise the source in three dimensions.