Tunable diode laser spectroscopy, is a precise method that utilizes lasers with a narrowband wavelength. The TDLAS sensor primarily comprises a laser light source, gas chamber, and photodiode.

The wavelength is adjusted to match the absorption optical spectra of the target gas by periodically modulating the input current. Following selective gas absorption, the remaining laser radiation will reach the photodiode and be detected. The absorption is determined based on the principles of the Beer-Lambert law. The level of absorption is determined by the optical path length inside the gas chamber and the absorption coefficient of the specific gas being measured.

Cubic TDLAS technology employs a lengthy laser light path via many reflections, allowing for precise measurement with a low range, an exceptional detection limit, and high-resolution quantification. The technology is widely used  for measurements of methane (CH4) moisture (H2O), carbon dioxide (CO2) etc.