The Differential Optical Absorbtion Spectroscopy (DOAS) technique is based on the phenomena of selective absorption of electromagnetic waves from gases. At interaction between radiation and atmospheric components, the UV-VIS molecular absorption is the main process for DOAS technique.

The DOAS system has three components, the emitter (xenon lamp and the collimating telescope), a receiver (telescope) and a spectral analyzer (monochromator).

The DOAS system has a capacity of measure of 200-750 m atmosphere path length, the time interval for one measurement of one (or several) gas concentration is not more than 3 minutes, 205-460 nm spectral range of measurements, 0.18 nm wavelength accuracy, up to 37 gases measured simultaneously, below 1 ppb detection limit.

The output data consist in gases concentration and their residuals.