Remote air pollution measurement

The availability of high energy tunable laser sources has extended the possibilities for remote air pollution measurement. This paper presents a discussion and comparison of the Raman method, the resonance and fluorescence backscatter method, long path absorption methods and the differential absorption method. A comparison of the above remote detection methods shows that the absorption methods offer the most sensitivity at the least required transmitted energy. Topographical absorption provides the advantage of a single ended measurement, and differential absorption offers the additional advantage of a fully depth resolved absorption measurement. Recent experimental results confirming the range and sensitivity of the methods are presented. Future widespread use of remote pollution monitoring will probably be limited to the infra-red to interact with molecular spectral bands and to meet eye safety requirements.