Concept and principle of operation

The FLAIR sensor system consists of an innovative 2D spectrometer system embedded on an airborne platform. Please, see the picture.

The general working principle is the following: a broad spectrum generated by a specifically designed supercontinuum laser (emitting at 2-5 µm or 8-12 µm) (A) propagates through a multipass cell (D) filled with air samples at reduced pressure. The output spectrum with absorption features from different molecular species is dispersed by a quasi 2D spectrometer based on a conventional dispersion grating with vertical averaging for noise reduction(C), and imaged onto an infrared detector array (B). The 2D absorption spectrum is then analysed (F) to provide information on the level of pollutants present in the air in front of the flying platform.

Today, significant effort is devoted globally to improve air quality through land-use planning strategies, replacement of fossil fuels by clean energy sources and lower level of industrial emission. In order to be successful, these measures need be accompanied by air quality monitoring at large scale to ensure compliance with air quality legislation but also to provide information for political decision making regarding air quality and safety. This is particularly challenging outside the dense urban network of air quality monitoring stations.

FLAIR aims at developing an airborne, compact and cost-effec­tive air quality sampling sensor for sensitive and selective detection of molecular fingerprints in the 2-5 μm and 8-12 μm infrared atmos­pheric transmission windows. The sensor is based on an innovative supercontinuum laser that provides ultra-bright emission across the spectrum of interest. In combination with a novel type of multipass cell and in conjunction with specifically developed uncooled detec­tor arrays this will enable highly sensitive detection. Broadband high resolution absorption spectra capture will allow for highly selective molecular detection in complex gas mixtures at the ppbv levels in real time. This high performance sensor constitutes a breakthrough in the field of trace gas spectroscopy. Moreover, in a hybrid approach, the main spectroscopic sensor will be complemented by a fine particle detector in order to obtain a complete picture of the air quality.

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