Coherent Anti-Stokes Raman Spectroscopic Probe of Combustion

It has already been demonstrated that ordinary Raman Spectroscopy can be used to measure multicylce averaged air/fuel distributions in suitable single cylinder engines with gaseous fuel and to measure concentrations of major stable species in laboratory flames. However, in hostile environments with relatively poor optical access, in the presence of fluorescing constituents of ordinary gasoline it will probably be necessary to use a more sophisticated technique known as Coherent Anti-Stokes Raman Spectroscopy to obtain concentrations and temperature distributions. The advantages of this technique to be described are its high signal output, excellent spatial and temporal resolution (single pulse measurements are possible), reduced optical access requirements and immunity from fluorescence interference. Means of implementing the technique with such high resolution, as well as results from measurements on a stable flame system are presented.