Study on application fourier transform filter to Differential optical absorption spectroscopy

The DOAS (differential optical absorption spectroscopy) technology is a new spectral measurement for analyzing gas concentration, using the gas narrow band absorption characteristics. This paper makes an analysis about the mathematics method of dealing with DOAS and presents a new way of Fourier transform filtering based on the characters of absorption across section and the absorbency for main polluted gas(SO₂, NO₂, NH₃ etc), finding the best wave band for differential optical absorption spectroscopy. The gas concentration can be figured out according to the different characteristics after Fourier transform. The method is good at reducing disturb from unknown gas which has different spectrum character while with the overlapping differential absorption spectrum with SO₂, NO₂ NH₃ etc. Finally, several questions were put forward about Fourier transform filter to DOAS.