Trace gas detection by the use of the optical parametric oscillator (OPO) technology
Chan, Chi Chiu.
Date of Issue2010
School of Chemical and Biomedical Engineering
The detection of trace gases is of highly importance for many applications in the fields of environments monitoring, chemical process control, homeland security, and bio-medical research. As we know the atom or molecule, is uniquely characterized by a set of levels of energy. transitions between levels by absorption or emission result in different features in the spectrum. These features are used for the identification and quantification of different molecular species. Therefore, by measuring the absorption spectrum of gas mixture, we can determine all the species and their concentrations in this. Because of the majority of gaseous chemicals exhibit fundamental vibrational absorption bands in the mid-infrared region(~2-25µm), the absorption of light by these fundamental wavelengths will provide us an universal method for detection.