Spatially resolved saturated absorption measurements of OH in methane-air flames.

A cross-beam saturated absorption spectroscopy technique, utilizing a single pulsed dye laser, has been developed for local concentration measurements in flames. With a differential detection of the probe and the reference laser beam intensities, a significant improvement of the technique has been achieved. In this work the basic theory of the method is discussed. Its use in combustion studies is demonstrated by presenting OH concentration profiles in two premixed laminar methane-air flames.